WO2022209992A1 - Ophthalmological device - Google Patents

Abstract

This ophthalmological device comprises: an eye refractive power measurement optical system that projects first measurement light onto the fundus of a subject eye and acquires the refractive power of the subject eye on the basis of reflected light generated by the first measurement light being reflected off of the fundus; a tomographic image capture optical system that projects second measurement light onto an anterior section of the subject eye and uses a light detector to detect the return light of the second measurement light in a direction inclined with respect to the projection optical axis of the second measurement light, thereby acquiring an anterior eye section tomographic image; and an eye axial length acquisition means that acquires the axial length of the subject eye on the basis of the refractive power of the eye and the anterior eye section tomographic image. The first measurement light is infrared light and the second measurement light is red visible light or infrared light, thereby reducing discomfort for the subject and acquiring the eye axial length at a high accuracy.

Description

ophthalmic equipment

The present disclosure relates to an ophthalmologic apparatus that acquires the axial length of an eye to be examined.

An ophthalmologic apparatus is known that illuminates the translucent body of the anterior segment of the eye to be examined in a manner that cuts the light and captures a cross-sectional image of the anterior segment. Visible light such as blue, green, and white light is projected onto the eye to be examined. In addition, in Patent Document 1, blue visible light is used.

JP 2019-134907 A

In the above-mentioned ophthalmologic apparatus, light having a wavelength suitable for photographing opacity in a translucent body is used to illuminate the anterior segment of the subject's eye, so the subject may feel glare. In particular, when a subject, such as a young person (including children), cannot tolerate the glare caused by the illumination, the imaging cannot be performed accurately and efficiently.

On the other hand, in recent years, the prevalence of myopia has increased significantly, mainly among young people, and attention is being paid to the evaluation of myopia progression based on the axial length of the eye. The inventors obtained both the ocular refractive power of the eye to be examined and the cross-sectional image of the anterior segment of the eye, and studied an apparatus configuration for obtaining the axial length based on these images. However, if the anterior segment cross-sectional image of the subject's eye is not properly photographed due to glare, it becomes difficult to acquire the axial length.

The present disclosure has been made in view of the above circumstances, and a technical problem is to provide an ophthalmologic apparatus that can reduce the burden on the subject and accurately acquire the axial length of the eye.

An ophthalmologic apparatus according to the present disclosure projects a first measurement light onto the fundus of an eye to be inspected, and measures the refractive power of the eye to be inspected based on the light reflected by the fundus from the first measurement light. and an eye refractive power measurement optical system for obtaining the second measurement light projected onto the anterior segment of the eye to be inspected, and the second measurement light projected onto the projection optical axis of the second measurement light. a cross-sectional image capturing optical system for obtaining a cross-sectional image of the anterior segment of the subject's eye by detecting returned light from an oblique direction with a photodetector; and an ocular length acquiring means for acquiring the axial length of the eye to be inspected based on the above, wherein the first measuring light is infrared light and the second measuring light is red It is characterized by being visible light or infrared light.

1 is an external view of an ophthalmologic apparatus; FIG. 1 is a schematic diagram showing an optical system of an ophthalmologic apparatus; FIG. FIG. 4 is a schematic diagram showing the relationship between the luminosity of an eye to be inspected and the wavelength; FIG. 3 is a schematic diagram showing the relationship between light sensitivity of an image sensor and wavelength. FIG. 2 is a simplified schematic diagram of a fixation target presenting optical system; FIG. 2 is a simplified schematic diagram of a target projection optical system; It is an example of the flowchart which shows the control action of an ophthalmologic apparatus. It is an example of a cross-sectional image of the anterior segment. It is a schematic diagram for demonstrating the derivation|leading-out method of eye axial length. FIG. 4 is a diagram showing refractive power in the meridional direction; It is an example of the flowchart which shows the control action of an ophthalmologic apparatus. It is an appropriate cross-sectional image taken in a state in which the subject's eye is not miotic. This is an inappropriate cross-sectional image taken with the subject's eye miotic. It is an example of measured values and effectiveness in a plurality of parameter information. It is an example of the flowchart which shows the control action of an ophthalmologic apparatus. It is the change in luminance value corresponding to the appropriate cross-sectional image. It is a change in brightness value corresponding to an inappropriate cross-sectional image. It is an example showing the temporal change of the axial length.

<Overview>
An outline of an ophthalmologic apparatus according to an embodiment of the present disclosure will be described. The items classified in <> below can be used independently or in conjunction with each other. In the present embodiment, "conjugated" is not necessarily limited to a perfect conjugated relationship, but includes "substantially conjugated". That is, the term "conjugated" in this embodiment also includes the case where the parts are displaced from the perfectly conjugated position within the range allowed in relation to the technical significance of each part.

The first embodiment will be described below. The ophthalmologic apparatus of this embodiment is an apparatus capable of acquiring the axial length of an eye to be examined. For example, the ophthalmic device may be configured to reduce glare due to illumination of the subject's eye. In other words, it may be configured to suppress miosis of the subject's eye. As a result, the eye refractive power of the subject's eye can be measured with high accuracy in the eye refractive power measurement optical system described later. In addition, in the cross-sectional image capturing optical system described later, it becomes easier to obtain a good cross-sectional image of the anterior segment of the subject's eye (for example, up to the posterior surface of the crystalline lens). As a result, the eye axial length can be accurately obtained based on the eye refractive power and the anterior segment cross-sectional image. It should be noted that reduction of glare as in the present embodiment is effective particularly when the subject cannot tolerate glare (for example, young people including children).

The ophthalmologic apparatus of this embodiment may have an optical system used to obtain the axial length of the eye and an axial length obtaining means.

<Eye refractive power measurement optical system>
The ophthalmologic apparatus of this embodiment may have an eye refractive power measurement optical system (for example, the measurement optical system 100). The eye refractive power measurement optical system is an optical system for acquiring the eye refractive power of the eye to be examined. For example, a configuration may be provided in which measurement light (first measurement light) is projected onto the fundus of the subject's eye, and the refractive power of the eye is obtained based on the reflected light of the measurement light reflected by the fundus. good.

The eye refractive power measuring optical system may be a measuring optical system used in an objective eye refractive power measuring device (autorefractometer, wavefront sensor, etc.). The projection optical axis of the first measurement light in the eye refractive power measurement optical system may be arranged on the plane of the light section formed by the cross-sectional image taking optical system, which will be described later. For this purpose, an eye refractive power measurement optical system is used to acquire the eye refractive power on the light-section plane of the anterior segment (surface eye refractive power). Of course, the eye refractive power measurement optical system may be capable of acquiring eye refractive power on other planes.

<Sectional imaging optical system>
The ophthalmologic apparatus of this embodiment may have a cross-sectional imaging optical system (for example, a cross-sectional imaging optical system). The cross-sectional image capturing optical system is an optical system for acquiring an anterior segment cross-sectional image of the subject's eye. For example, measuring light is projected toward the anterior segment of the eye to be inspected, and return light (scattered light) due to scattering of the measuring light is detected from an oblique direction with respect to the projection optical axis of the measuring light. A configuration for acquiring an eye cross-sectional image may be provided. Further, for example, the measurement light (second measurement light) is projected onto the anterior segment of the subject's eye to form a light section passing through the optical axis of the eye refractive power measurement optical system in the anterior segment, 2 A configuration for acquiring an anterior segment cross-sectional image based on scattered light from the light-section plane of the measurement light may be provided.

The cross-sectional imaging optical system may be an optical system based on the Scheimpflug principle. In this case, the projection optical axis of the first measurement light in the eye refractive power measurement optical system and the projection optical axis of the second measurement light in the cross-sectional imaging optical system may be arranged coaxially. Further, in this case, the second measurement light may be projected as slit light in the cross-sectional imaging optical system. For example, the irradiation area of the slit light is set as the light cutting plane of the anterior segment. Further, in this case, the cross-sectional image capturing optical system may have a lens system and a photodetector arranged in a Scheimpflug relationship with the light section formed in the anterior segment. For example, the photodetector may be a two-dimensional imager. The light-receiving optical axis of the second measurement light is arranged so as to be inclined with respect to the light section plane.

In addition, it is preferable that the imaging range of the anterior segment cross-sectional image by the cross-sectional image capturing optical system includes from the front surface of the cornea to at least the front surface of the crystalline lens of the subject's eye. Needless to say, it is more preferable if the area from the anterior surface of the cornea to the posterior surface of the lens is included. In this case, since the corneal thickness, the anterior corneal curvature radius, the posterior corneal curvature radius, the anterior chamber depth, the lens thickness, the anterior lens curvature radius, and the posterior lens curvature radius can be obtained without omission, the axial length can be determined more appropriately. can ask.

<First measurement light and second measurement light>
In this embodiment, the first measurement light in the eye refractive power measurement optical system may be composed of light having a wavelength at which the subject's eye does not perceive glare. For example, the first measurement light may be infrared light (any one of near-infrared light, mid-infrared light, and far-infrared light). As a result, the examinee does not feel glare when the first measurement light is projected, suppresses miosis, and accurately obtains the refractive power of the eye.

In the present embodiment, the second measurement light in the cross-sectional image capturing optical system may be composed of light having a wavelength at which the subject's eye does not feel glare. For example, the second measurement light may consist of red visible light. Visibility to red visible light is low, making it difficult to feel glare. Also, for example, the second measurement light may be composed of infrared light (any one of near-infrared light, mid-infrared light, and far-infrared light). Visibility to infrared light is approximately 0, and no glare is felt. Therefore, the subject does not feel (hardly feels) glare when the second measurement light is projected, and the frequency of imaging failure due to turning away or blinking is reduced. As a result, an anterior segment cross-sectional image can be captured with high accuracy.

In the eye refractive power measuring optical system and the cross-sectional imaging optical system, it is possible to use infrared light for the first measuring light and the second measuring light. The second wavelengths of the measurement light may be the same wavelength or different wavelengths. For example, when the first wavelength and the second wavelength are different wavelengths, the second wavelength may be shorter than the first wavelength, or the second wavelength may be longer than the first wavelength. may As a result, mutual interference of infrared light is suppressed, and measurement accuracy is improved.

In this embodiment, the second wavelength of the second measurement light may be shorter than the first wavelength of the first measurement light. More specifically, in the wavelength range of red visible light to infrared light corresponding to the first measurement light and the second measurement light, the first wavelength is set on the long wavelength side with low luminosity, and the short wavelength with high luminosity is set. A second wavelength may be set on the wavelength side. For example, since the first measurement light is focused on the fundus and the second measurement light is focused on the anterior segment of the eye, the first measurement light is more likely to cause glare than the second measurement light. By setting the wavelength in this manner, the burden on the subject is further reduced.

For example, near-infrared light may be used as the first measurement light. As an example, the first wavelength of the first measurement light may have a peak wavelength between 800 nm and 900 nm. In this case, in the eye refractive power measurement optical system, a light source having an emission wavelength with a lower limit of 800 nm and an upper limit of 900 nm may be used. In addition, a light source is used in which the lower limit of the emission wavelength is shorter than 800 nm and the upper limit is longer than 900 nm, and light with a wavelength shorter than 800 nm and light with a wavelength longer than 900 nm are emitted in the optical path. It may be cut by an optical member (for example, a cut filter or the like).

For example, red visible light or near-infrared light may be used as the second measurement light. As an example, the second wavelength may have a peak wavelength between 650 nm and 800 nm. Preferably, it should have a peak wavelength between 700 nm and 750 nm, which has less effect on miosis. In this case, in the cross-sectional imaging optical system, a light source having an emission wavelength with a lower limit of 700 nm and an upper limit of 750 nm may be used. In addition, a light source is used in which the lower limit of the emission wavelength is shorter than 700 nm and the upper limit is longer than 750 nm, and light with a wavelength shorter than 700 nm and light with a wavelength longer than 750 nm are emitted in the optical path. It may be cut by an optical member.

For example, by using near-infrared light as the first measurement light and red visible light or near-infrared light as the second measurement light, the subject is less likely to feel glare and has various wavelength sensitivity ranges. can be used (details below).

In this embodiment, as the second measurement light that can be projected by the cross-sectional imaging optical system, light having the second wavelength (that is, red visible light or infrared light) and light having a wavelength different from the second wavelength are used. At least two types of measurement light may be provided. For example, the light having a wavelength different from the second wavelength may be light considering the wavelength transmittance (scattering component) of the subject's eye. As an example, at least one of visible light such as blue visible light, green visible light, and white visible light may be used. If the light having the second wavelength is infrared light, it is also possible to use red visible light as light having a wavelength different from the second wavelength.

For example, the longer the wavelength of the second measurement light, the more effective it is in reducing glare, but the cross-sectional image of the anterior segment tends to be dark because it is less likely to scatter. For this reason, the second measurement light includes light having a second wavelength (red visible light or infrared light) that prioritizes reduction of glare, and light having a wavelength different from the second wavelength. and a light giving priority to the brightness of the cross-sectional image may be provided. For example, if the subject's eye suffers from cataract disease, the light of the second wavelength is transmitted more than the visible light even if there is turbidity, and the cross-sectional image of the anterior segment is not very bright, which may make diagnosis of cataract difficult. For this reason, the second measurement light may be provided with light of a wavelength different from the second wavelength, which is suitable for photographing turbidity, together with the light of the second wavelength. For example, by selectively projecting the light of the second wavelength and the light of a wavelength different from the second wavelength, it is possible to obtain a good cross-sectional image of the anterior segment. good.

<Photodetector>
The photodetector of the cross-sectional imaging optical system may be composed of a detector having a wavelength sensitivity range with respect to the second measurement light (second wavelength). That is, a detector with a wavelength sensitivity range for red visible light, a detector with a wavelength sensitivity range for infrared light, a detector with a wavelength sensitivity range for red visible light and infrared light, etc. It may consist of either.

The detector may be equipped with a semiconductor substrate made of various elements. The semiconductor may be made of a single element. For example, silicon (Si), germanium, selenium, or the like can be used as the material. As an example, a photodetector using a semiconductor made of Si as a substrate (hereinafter referred to as a Si image sensor) exhibits sensitivity to wavelengths including the ultraviolet region to the infrared region. Although the sensitivity to red visible light and infrared light is reduced, these lights can be detected, and an anterior segment cross-sectional image can be obtained. Of course, in addition to ordinary Si, a photodetector with improved sensitivity to infrared light may be used by using a semiconductor substrate made of black Si.

In addition, the semiconductor may be one made of multiple elements (so-called compound semiconductor). In this case, a material that combines iridium, gallium, and arsenic (InGaAs), a material that combines indium and antimony (InSb), a material that combines mercury, cadmium, and tellurium (HgCdTe), etc. can be used. . In addition to these, a multi-element material containing silicon may be used. As an example, a photodetector using a semiconductor made of InGaAs as a substrate (hereinafter referred to as an InGaAs image sensor) exhibits sensitivity to wavelengths from the visible range (red visible range) to the infrared range. It has high sensitivity to red visible light and infrared light, and can acquire cross-sectional images of the anterior segment.

In addition, if ophthalmic equipment becomes expensive, it may hinder the spread of the equipment, so there is a possibility that the acquisition of the axial length will not be performed at the appropriate time. For example, in response to the global issue of increasing myopia prevalence, especially among young people, the evaluation of myopia progression based on the axial length of the eye is attracting attention. Without it, the chances of obtaining the axial length would be reduced. In this embodiment, the cost of the device can be reduced by using a Si image sensor, which is less expensive than an InGaAs image sensor but has lower detection sensitivity, as a photodetector of the cross-sectional image capturing optical system.

<Axial Length Acquisition Means>
The ophthalmologic apparatus of the present embodiment may include axial length acquisition means (for example, control unit 50). For example, the axial length obtaining means may also serve as an image processing section, an axial length obtaining section, an arithmetic control section, and the like.

The eye axial length acquisition means may acquire the eye refractive power of the subject's eye by controlling acquisition of the eye refractive power using the eye refractive power measurement optical system. More specifically, by controlling the projection of the first measurement light in the eye refractive power measurement optical system and the detection by the photodetector of the fundus reflected light of the first measurement light, the eye refractive power of the subject's eye is measured. may be obtained.

Further, the axial length acquiring means may acquire the anterior segment cross-sectional image of the eye to be examined by controlling the acquisition of the anterior segment cross-sectional image using the cross-sectional image capturing optical system. More specifically, by controlling the projection of the second measurement light in the cross-sectional imaging optical system and the detection of the return light (scattered light) of the second measurement light by the photodetector, Partial cross-sectional images may be acquired.

The axial length obtaining means calculates the axial length of the subject's eye based on the eye refractive power obtained using the eye refractive power measuring optical system and the anterior segment cross-sectional image obtained using the cross-sectional image capturing optical system. You can get the length. In other words, the axial length of the subject's eye may be obtained in a state in which the glare caused by the projection of the first measurement light and the second measurement light onto the subject is reduced and the burden on the subject is reduced.

The axial length acquiring means may acquire the axial length based on the ocular refractive power of the subject's eye and the anterior segment cross-sectional image. For example, the eye axial length may be derived by ray tracing calculation based on the eye refractive power and the anterior segment cross-sectional image. In the ray tracing calculation, the distance between the point of intersection and the vertex of the cornea when a light ray incident on a predetermined position of the anterior segment from the far point is refracted by the translucent body and intersects the optical axis is derived as the axial length of the eye. be. At this time, instead of the equivalent spherical power that is generally used when specifying the far point in the field of ophthalmology, the eye refractive power at the light-section plane (surface eye refractive power) may be used. As a result, the position of the far point of the light ray passing through the cut plane can be specified more properly. As a result, the axial length can be determined more appropriately. At this time, a ray tracing calculation may be performed for each of the plurality of rays, and the axial length of the eye may be obtained as a result of the ray tracing calculation for each ray. For example, an average value (or a weighted average) of the axial lengths obtained by each ray tracing calculation may be obtained as the axial length of the subject's eye.

In the ray tracing calculation, the incident position of the ray with respect to the boundary surface of each transparent body and the angle change at the boundary surface are determined by considering the shape of the transparent body at the cut surface specified from the anterior segment information. may be The ray tracing calculation may also take into account the decentration of the anterior segment translucent body. Eccentricity is identified based on the anterior segment information. As a result of considering the eccentricity of the transmissive body in the cut plane, the axial length can be obtained more appropriately. In this case, for example, a ray tracing calculation is performed for each of a plurality of rays including at least the first ray and the second ray to obtain the axial length for each ray, and based on the plurality of axial lengths, the final measurements may be obtained. The first light ray and the second light ray are light rays arranged on the cutting plane with the eye axis interposed therebetween.

In the cross-sectional image capturing optical system, the axial length obtaining means obtains at least light of a second wavelength (red visible light or infrared light) as the second measurement light and light having a wavelength different from the second wavelength. Switching between two types of measurement light may be controlled. For example, if the cross-sectional imaging optical system is equipped with one light source capable of projecting measurement light containing each wavelength (for example, a light source that projects white visible light), the wavelength for converting the wavelength of the light source The converter may be controlled, or the insertion/removal of an optical member arranged in the optical path of the measurement light may be controlled. The optical member may be a cut filter, a dichroic mirror, or the like. Further, for example, when the cross-sectional imaging optical system includes a plurality of light sources capable of projecting measurement light of each wavelength, turning on and off of the plurality of light sources may be controlled. For example, this makes it possible to selectively use two types of measurement light depending on the condition of the eye to be examined, and efficiently acquire the axial length.

The axial length obtaining means continuously projects the second measurement light and continuously detects the return light of the second measurement light in the cross-sectional image capturing optical system, and obtains a plurality of cross-sectional images of the anterior segment. may be obtained. In this case, the eye axial length acquisition means executes the projection of the second measurement light and the detection of the return light in real time, and captures the anterior segment cross-sectional images as a moving image to obtain a plurality of anterior segment cross-sectional images. Images may be acquired. Further, in this case, the axial length acquisition means executes the projection of the second measurement light and the detection of the return light at predetermined time intervals (for example, at intervals of 1 second, etc.). A plurality of anterior segment cross-sectional images may be acquired by capturing the image as a still image.

In the present embodiment, since the second measurement light has a wavelength that reduces glare, it is possible to continuously acquire a plurality of cross-sectional images of the anterior segment easily. Since the pupillary condition (miosis and mydriasis) and the accommodation condition of the eye to be examined change over time, any configuration that acquires a plurality of cross-sectional images of the anterior segment may be suitable for the condition of the eye to be examined. It is also possible to select an anterior segment cross-sectional image and acquire the eye axial length based on this.

The axial length acquisition means may perform arithmetic processing based on a plurality of cross-sectional images of the anterior segment. For example, the arithmetic processing may be processing for obtaining a representative value (eg, average value, median value, mode value, maximum value, minimum value, etc.). For example, arithmetic processing may be processing for obtaining variations (eg, variance, standard deviation, standard error, coefficient of variation, etc.). Of course, various processes may be combined and executed, or processes different from these may be executed.

The axial length acquisition means may perform arithmetic processing on a plurality of anterior segment cross-sectional images. For example, the axial length acquisition means may obtain a single anterior segment cross-sectional image (composite cross-sectional image) by averaging a plurality of anterior segment cross-sectional images. In addition, at this time, by analyzing variations in the plurality of anterior eye segment cross-sectional images (for example, variations in luminance information), those inappropriate for the averaging process may be excluded. Thereby, the eye axial length based on the ocular refractive power of the subject's eye and the synthesized cross-sectional image may be obtained.

Further, the axial length acquisition means may perform arithmetic processing on shape information regarding the shape of the anterior segment, which can be obtained by analyzing a plurality of cross-sectional images of the anterior segment. The shape information may be any information that can specify the shape of the translucent body included in the anterior segment. For example, it may be a parameter representing the shape of each translucent body (for example, curvature, thickness, depth, etc.). Also, the shape information may include multiple parameters. That is, one or more parameters may be acquired for each anterior segment cross-sectional image.

In this case, the axial length obtaining means may obtain a parameter for each anterior segment cross-sectional image and calculate a representative value of the parameter. Variations in parameters may be obtained, and those inappropriate for calculation of the representative value may be excluded. Note that it is not always necessary to calculate the representative values for all parameters that can be analyzed from the anterior segment cross-sectional image, and the representative values for only some parameters may be calculated. Thereby, the eye axial length based on the ocular refractive power of the subject's eye and one or more parameters obtained from the anterior segment cross-sectional image may be obtained.

Further, the axial length acquisition means may perform arithmetic processing on the axial length based on the eye refractive power of the subject's eye and a plurality of anterior segment cross-sectional images. In other words, arithmetic processing may be performed on the axial length derived using each parameter for each anterior segment cross-sectional image. In this case, the axial length obtaining means may calculate a representative value from each axial length. Of course, variations in axial length may be obtained, and those inappropriate for calculation of the representative value may be excluded.

The axial length acquisition means may be configured to execute at least one of arithmetic processing for multiple anterior segment cross-sectional images, arithmetic processing for shape information, arithmetic processing for axial length, and the like. By executing these arithmetic processes, the axial length can be obtained with high accuracy. For example, the accuracy of the eye axial length is improved because the influence of the movement of the subject's face, the pupillary state and accommodation state of the subject's eye, the resolution of the detector, and the like is reduced by arithmetic processing. Since arithmetic processing on the anterior segment cross-sectional image tends to be complicated, the axial length can be efficiently obtained by executing arithmetic processing on the shape information and the axial length.

Also, for these calculation processes, it is not always necessary to use the eye refractive power obtained with infrared light, the cross-sectional image of the anterior segment obtained with red visible light or infrared light, and the like. That is, for example, eye refractive power obtained with light having a wavelength different from infrared light may be used, or an anterior segment cross-sectional image obtained with light having a wavelength different from red visible light or infrared light may be used. may be used. However, with light having different wavelengths, miosis and blinking caused by the subject feeling glare from the light tend to affect the accuracy of the axial length of the eye. Therefore, it is preferable to use infrared light or red visible light as in this embodiment.

The eye axial length acquisition means may concurrently acquire the eye refractive power using the eye refractive power measurement optical system and acquire the anterior segment cross-sectional image using the cross-sectional image capturing optical system. For example, the eye axial length acquisition means can detect the detection timing of the photodetector of the eye refractive power measurement optical system and the cross-sectional image taking optical system in a state in which measurement light is projected from both optical systems onto the eye to be examined. The detection timing of the photodetector may be the same timing (in parallel). Note that the term "same" as used herein does not necessarily mean that the respective detection timings are exactly the same. For example, there may be a time difference that does not cause a significant difference in the state of the subject's eye (pupil state or accommodative state) between the respective detection timings.

In this embodiment, both the first measurement light in the eye refractive power measurement optical system and the second measurement light in the cross-sectional imaging optical system have wavelengths that reduce glare, so both measurement lights are projected. As for the state, the burden on the examinee is small. In addition, by setting the detection timing of the photodetector of the eye refractive power measurement optical system and the photodetector of the cross-sectional image capturing optical system to be the same timing, the eye refractive power and the anterior segment cross-sectional image obtained by , there is no deviation in the state of the eye to be examined. For example, by using such an eye refractive power and an anterior segment cross-sectional image, it is possible to improve the accuracy of the eye axial length.

The second embodiment will be described below. The ophthalmologic apparatus of this embodiment is an apparatus capable of measuring the axial length of an eye to be examined. For example, the ophthalmologic apparatus may have an optical system, state information obtaining means, shape information obtaining means, axial length obtaining means, and the like used for measuring the axial length of the eye.

<Eye refractive power measurement optical system>
The ophthalmologic apparatus of this embodiment may have an eye refractive power measurement optical system (for example, the measurement optical system 100). The eye refractive power measurement optical system is an optical system for acquiring the eye refractive power of the eye to be examined. For example, a configuration may be provided in which measurement light (first measurement light) is projected onto the fundus of the subject's eye, and the refractive power of the eye is obtained based on the reflected light of the measurement light reflected by the fundus. good. Note that the first measurement light may be visible light or infrared light.

The eye refractive power measuring optical system may be a measuring optical system used in an objective eye refractive power measuring device (autorefractometer, wavefront sensor, etc.). The projection optical axis of the first measurement light in the eye refractive power measurement optical system may be arranged on the plane of the light section formed by the cross-sectional image taking optical system, which will be described later. For this purpose, an eye refractive power measurement optical system is used to acquire the eye refractive power on the light-section plane of the anterior segment (surface eye refractive power). Of course, the eye refractive power measurement optical system may be capable of acquiring eye refractive power on other planes.

<Sectional imaging optical system>
The ophthalmologic apparatus of this embodiment may have a cross-sectional imaging optical system (for example, a cross-sectional imaging optical system). The cross-sectional image capturing optical system is an optical system for acquiring an anterior segment cross-sectional image of the subject's eye. For example, measuring light is projected toward the anterior segment of the eye to be inspected, and return light (scattered light) due to scattering of the measuring light is detected from an oblique direction with respect to the projection optical axis of the measuring light. A configuration for acquiring an eye cross-sectional image may be provided. Further, for example, the measurement light (second measurement light) is projected onto the anterior segment of the subject's eye to form a light section passing through the optical axis of the eye refractive power measurement optical system in the anterior segment, 2 A configuration for acquiring an anterior segment cross-sectional image based on scattered light from the light-section plane of the measurement light may be provided. The measurement light (second measurement light) may be visible light or infrared light.

The cross-sectional imaging optical system may be an optical system based on the Scheimpflug principle. In this case, the projection optical axis of the first measurement light in the eye refractive power measurement optical system and the projection optical axis of the second measurement light in the cross-sectional imaging optical system may be arranged coaxially. Further, in this case, the second measurement light may be projected as slit light in the cross-sectional imaging optical system. For example, the irradiation area of the slit light is set as the light cutting plane of the anterior segment. Further, in this case, the cross-sectional image capturing optical system may have a lens system and a photodetector arranged in a Scheimpflug relationship with the light section formed in the anterior segment. For example, the photodetector may be a two-dimensional imager. The light-receiving optical axis of the second measurement light is arranged so as to be inclined with respect to the light section plane.

In addition, it is preferable that the imaging range of the anterior segment cross-sectional image by the cross-sectional image capturing optical system includes from the front surface of the cornea to at least the front surface of the crystalline lens of the subject's eye. Needless to say, it is more preferable if the area from the anterior surface of the cornea to the posterior surface of the lens is included. In this case, since the corneal thickness, the anterior corneal curvature radius, the posterior corneal curvature radius, the anterior chamber depth, the lens thickness, the anterior lens curvature radius, and the posterior lens curvature radius can be obtained without omission, the axial length can be determined more appropriately. can ask.

<Front image capturing optical system>
The ophthalmologic apparatus of this embodiment may have a front imaging optical system (for example, front imaging optical system 200). The front image capturing optical system is an optical system for acquiring a front observation image of the subject's eye. For example, a configuration for acquiring a front observation image by illuminating the anterior segment of the subject's eye may be provided.

<State information acquisition means>
The ophthalmologic apparatus of this embodiment may include state information acquisition means (for example, the control unit 50). The state information acquiring means acquires state information relating to the state of the anterior segment of the subject's eye, including at least one of the pupillary state and the accommodation state. For example, the pupil state may be at least one of a miotic state and a mydriatic state. Also, for example, the adjustment state may be at least one of a state in which the adjustment is activated and a state in which the adjustment is released.

The state information acquisition means may acquire information that enables to grasp the presence or absence of miosis and mydriasis as the pupillary state. For example, values such as pupil diameter may be used for such information. Further, a determination result obtained by determining the presence or absence of miosis or mydriasis based on the value of the pupil diameter may be used. The state information acquisition means may acquire information that enables the presence or absence of adjustment to be grasped as the adjustment state. In this case, at least one of the depth of the anterior chamber, the anterior curvature of the lens, the posterior curvature of the lens, the thickness of the lens, and the like may be used. Also, a determination result obtained by determining the presence or absence of accommodation based on values such as the anterior curvature of the lens, the posterior curvature of the lens, the thickness of the lens, and the like may be used.

The state information acquisition means may acquire the state information by analyzing the anterior segment cross-sectional image acquired using the cross-sectional image capturing optical system. Alternatively, the state information may be acquired by analyzing a frontal image of the anterior segment acquired using a frontal image capturing optical system. Alternatively, the state information may be acquired by an input by the examiner using an operation means (for example, the monitor 16). Alternatively, the state information may be acquired by receiving the state information acquired by a device other than the ophthalmologic device. For example, in this case, information such as minor pupil may be received.

In the present embodiment, the state information acquisition means acquires at least one of the anterior segment cross-sectional image acquired by the cross-sectional image capturing optical system and the anterior segment front image captured by the front image capturing optical system. status information may be obtained based on the For example, the axial length of the eye can be obtained more accurately by obtaining the state of the anterior segment in real time using these optical systems provided in the ophthalmologic apparatus and reflecting it in deriving the axial length of the eye.

In addition, in the present embodiment, the state information obtaining means obtains the first state information regarding the first state of the anterior segment at the timing of obtaining the eye refractive power and the second state of the anterior segment at the timing of obtaining the cross-sectional image of the anterior segment. and second state information relating to. The first state and the second state do not necessarily match and may be different states. That is, in the first state and the second state, the pupil state may be different, and the accommodation state may be different. Of course, the first state and the second state may be the same state. Since there may be a discrepancy in the state of the anterior segment between acquisition of the eye refractive power and acquisition of the cross-sectional image of the anterior segment, the condition information of both can be obtained by acquiring the condition information at each timing. can be easily compared and the axial length can be obtained more accurately.

<Shape Information Acquisition Means>
The ophthalmologic apparatus of this embodiment may include shape information acquisition means (for example, the control unit 50). The shape information acquiring means may acquire shape information relating to the shape of the anterior segment, the shape information including a plurality of parameters, by analyzing the anterior segment cross-sectional image. Note that the plurality of parameters are parameters including at least the cornea and the lens. For example, the shape information may be any information that can specify the shape of the translucent body included in the anterior segment. As an example, coordinates at which each transparent body is located, equations representing the shape of each transparent body, and values obtained from the equations (for example, curvature, thickness, depth, etc.), and the like may be used.

A plurality of parameters included in the shape information may include parameters related to the shape of the cornea. Examples include the radius of curvature of the anterior surface of the cornea, the radius of curvature of the posterior surface of the cornea, the corneal thickness, and the like. Also, the plurality of parameters may include parameters relating to the shape of the lens. For example, the radius of curvature of the anterior surface of the lens, the radius of curvature of the posterior surface of the lens, the thickness of the lens, and the like. Also, the plurality of parameters may include a parameter relating to the depth of the anterior segment. For example, an anterior chamber depth and the like can be mentioned.

Although it is desirable to obtain more parameters (in other words, measured values) of the translucent body from the anterior segment cross-sectional image analyzed by the shape information obtaining means, if the parameters cannot be obtained as an analysis result , if the parameters are not exact, etc. For example, this varies depending on the condition of the anterior segment of the subject's eye, and effective parameters and ineffective parameters may coexist when an anterior segment cross-sectional image cannot be acquired appropriately. However, in the present embodiment, the axial length can be accurately measured by selecting parameters suitable for deriving the axial length by the axial length obtaining means, which will be described later.

<Axial Length Acquisition Means>
The ophthalmologic apparatus of the present embodiment may include axial length acquisition means (for example, control unit 50). For example, the axial length obtaining means may also serve as an image processing section, an axial length obtaining section, an arithmetic control section, and the like.

The eye axial length acquisition means may acquire the eye refractive power of the subject's eye by controlling acquisition of the eye refractive power using the eye refractive power measurement optical system. More specifically, by controlling the projection of the first measurement light in the eye refractive power measurement optical system and the detection by the photodetector of the fundus reflected light of the first measurement light, the eye refractive power of the subject's eye is measured. may be obtained.

Further, the axial length acquiring means may acquire the anterior segment cross-sectional image of the eye to be examined by controlling the acquisition of the anterior segment cross-sectional image using the cross-sectional image capturing optical system. More specifically, by controlling the projection of the second measurement light in the cross-sectional imaging optical system and the detection of the return light (scattered light) of the second measurement light by the photodetector, Partial cross-sectional images may be acquired.

Further, the axial length acquisition means may acquire the front image of the anterior segment by controlling the acquisition of the front image of the anterior segment using the front image capturing optical system.

The axial length acquisition means may acquire the axial length based on the refractive power of the eye to be examined and a plurality of parameters. For example, the eye axial length may be derived by ray tracing calculations based on the eye refractive power and a plurality of parameters. In the ray tracing calculation, the distance between the point of intersection and the vertex of the cornea when a light ray incident on a predetermined position of the anterior segment from the far point is refracted by the translucent body and intersects the optical axis is derived as the axial length of the eye. be. At this time, instead of the equivalent spherical power that is generally used when specifying the far point in the field of ophthalmology, the eye refractive power at the light-section plane (surface eye refractive power) may be used. As a result, the position of the far point of the light ray passing through the cut plane can be specified more properly. As a result, the axial length can be obtained more appropriately. At this time, a ray tracing calculation may be performed for each of the plurality of rays, and the axial length of the eye may be obtained as a result of the ray tracing calculation for each ray. For example, an average value (or a weighted average) of the axial lengths obtained by each ray tracing calculation may be obtained as the axial length of the subject's eye.

In the ray tracing calculation, the incident position of the ray with respect to the boundary surface of each transparent body and the angle change at the boundary surface are determined by considering the shape of the transparent body at the cut surface specified from the anterior segment information. may be The ray tracing calculation may also take into account the decentration of the anterior segment translucent body. Eccentricity is identified based on the anterior segment information. As a result of considering the eccentricity of the transmissive body in the cut plane, the axial length can be obtained more appropriately. In this case, for example, a ray tracing calculation is performed for each of a plurality of rays including at least the first ray and the second ray to obtain the axial length for each ray, and based on the plurality of axial lengths, the final measurements may be obtained. The first light ray and the second light ray are light rays arranged on the cutting plane with the eye axis interposed therebetween.

In this embodiment, the axial length acquisition means selects a selection parameter to be used for deriving the axial length from among a plurality of parameters in the shape information acquired by the shape information acquisition means. For example, the axial length acquisition means may select a selection parameter from among a plurality of parameters based on the state information of the anterior segment acquired by the state information acquisition means. As a result, even if the condition of the anterior segment of the subject's eye influences and invalid parameters are mixed in the shape information, the axial length can be accurately measured by excluding them.

The axial length acquisition means may associate in advance a selection parameter used for deriving the axial length with the state information of the anterior segment. For example, the axial length acquisition means may associate a selection parameter for deriving the axial length, which is selected from parameters that can be acquired as shape information, according to the pupillary state of the anterior segment. As an example, a predetermined selection parameter may be set according to the presence or absence of miosis or mydriasis. Further, as an example, a predetermined selection parameter may be set according to the degree of miosis or mydriasis. In this case, the selection parameter may be set when the degree of miosis or mydriasis exceeds a certain threshold, or the selection parameter may be set to change according to the degree of miosis or mydriasis. may be

Similarly, for example, the axial length acquiring means associates a selection parameter for deriving the axial length, which is selected from parameters that can be acquired as shape information, according to the accommodation state of the anterior segment. good too. As an example, predetermined selection parameters may be set according to the presence or absence of adjustment. Also, as an example, a predetermined selection parameter may be set according to the degree of adjustment. In this case, the selection parameter may be set when the degree of adjustment exceeds a certain threshold, or may be set so that the selection parameter changes according to the degree of adjustment.

The axial length obtaining means may associate in advance a non-selected parameter that is different from the selected parameter and is not used for deriving the axial length, with the state information of the anterior segment. . Of course, both the selected parameter and the non-selected parameter may be associated with the state information of the anterior segment.

Further, in the present embodiment, the axial length acquiring means changes non-selected parameters not used for deriving the axial length from the measured values to the assumed values among the plurality of parameters in the shape information acquired by the shape information acquiring means. You may For example, the hypothetical value may be a standard value adopted by a predetermined eye optical model (for example, the Gullstrand model eye, etc.). Moreover, the average value based on the statistical data etc. regarding eyes may be used. Alternatively, it may be an estimated value that can be obtained in consideration of effective measured values set as selection parameters and general ratios of the anterior and posterior surfaces of the cornea and the anterior and posterior surface of the lens in the eye. Alternatively, the measured value of the subject's eye obtained in the past by at least one of an ophthalmic device and a device different from the ophthalmic device may be used. A plurality of standard values and average values may be prepared for at least one of age, sex, region, etc., and the examiner can select based on which value the axial length is calculated. good.

The axial length acquisition means may acquire the axial length based on the measured values of the selected parameters for deriving the axial length and the assumed values of the non-selected parameters. Although the axial length can be obtained by using selected parameters (measured values), the accuracy of the axial length is improved by additionally using non-selected parameters (assumed values).

The non-selected parameters that are not used for deriving the axial length of the eye may be parameters of a translucent body located deeper than the iris of the subject's eye and containing the crystalline lens. For example, the condition of the anterior segment of the subject's eye tends to affect deeper regions of the subject's eye. In particular, the parameters of transparent bodies, including lenses, may not be obtained well. By replacing the measured values of such parameters with assumed values, the eye axial length can be obtained with higher accuracy than when the measured values are used as they are.

The eye axial length acquisition means acquires the eye refractive power using the eye refractive power measurement optical system and acquires the anterior segment cross-sectional image using the cross-sectional image capturing optical system at the anterior eye at the eye refractive power acquisition timing. It may be executed in a state where the first state of the eye part and the second state of the anterior eye part at the acquisition timing of the cross-sectional image of the anterior eye part match. In this case, the eye axial length obtaining means may perform at least one of obtaining the eye refractive power and obtaining the cross-sectional image of the anterior segment a plurality of times. For example, in the eye refractive power measurement optical system, the first measurement light may be continuously projected and the fundus reflected light of the first measurement light may be continuously detected to acquire the eye refractive power multiple times. . Further, for example, in the cross-sectional image capturing optical system, the second measurement light is continuously projected, and the return light of the second measurement light is continuously detected to acquire a plurality of anterior segment cross-sectional images. good too. At this time, the projection of the second measurement light and the detection of its return light are executed in real time, and the anterior segment cross-sectional images are captured as moving images, thereby acquiring a plurality of anterior segment cross-sectional images. good too. Projection of the second measurement light and detection of its return light are performed at predetermined time intervals (for example, at intervals of 1 second, etc.), and an anterior segment cross-sectional image is captured as a still image, thereby obtaining a plurality of images. anterior segment cross-sectional image may be acquired.

For example, the eye axial length acquisition means may first acquire either the eye refractive power or the anterior segment cross-sectional image. In this case, the detection timing of the photodetector included in the cross-sectional image capturing optical system is controlled so that the second state during acquisition of the anterior segment cross-sectional image matches the first state during acquisition of the eye refractive power. may Further, the detection timing of the photodetector of the eye refractive power measurement optical system is controlled so that the first state when acquiring the eye refractive power matches the second state when acquiring the anterior segment cross-sectional image. may The accuracy and reproducibility of the axial length can be improved by taking into account the state of the anterior segment of the subject's eye and acquiring the eye refractive power and the anterior segment image under the same state information.

Also, for example, the eye axial length acquisition means may acquire the eye refractive power and acquire the anterior segment cross-sectional image in parallel. In this case, the acquisition means obtains the detection timing of the photodetector of the eye refractive power measurement optical system and the light of the cross-sectional image taking optical system in a state in which measurement light is projected from both optical systems onto the eye to be examined. The detection timing of the detector may be the same timing (in parallel). Note that the term "same" as used herein does not necessarily mean that the respective detection timings are exactly the same. For example, there may be a time difference that does not cause a significant difference in the state of the subject's eye (pupil state or accommodative state) between the respective detection timings. By synchronizing the detection timings of the photodetectors included in the respective optical systems, there is no deviation in the state of the subject's eye between the acquired eye refractive power and the acquired anterior segment cross-sectional image. By using such an eye refractive power and an anterior segment cross-sectional image, it is possible to improve the accuracy of the axial length.

In this embodiment, by controlling both the cross-sectional image capturing optical system and the eye refractive power measuring optical system, the eye refraction of the eye to be examined is calculated based on the second state of the anterior segment when the anterior segment cross-sectional image is acquired. Power may be obtained. In this case, the axial length acquiring means acquires a plurality of anterior segment cross-sectional images as described above, and acquires the second state (pupil state and accommodation state), the refractive power of the eye may be acquired at the timing when the anterior segment cross-sectional image appropriate for the second state is obtained. Further, in this case, the eye axial length acquisition means acquires the eye refractive power at the same timing as the acquisition of the plurality of anterior eye segment cross-sectional images (in parallel), and obtains each of the anterior eye segment cross-sectional images and the eye refractive power. Each timing may be linked and stored. The eye axial length acquisition means considers the second state acquired for each of the plurality of anterior segment cross-sectional images, and selects an anterior segment cross-sectional image with an appropriate second state to associate with it. The measured eye refractive power may be obtained. The anterior segment cross-sectional image suitable for the second state is an anterior segment cross-sectional image representing a state in which accommodation is canceled by fogging using the eye refractive power measurement optical system (in other words, a state in which the lens thickness is thin). It may be an image. For example, in obtaining the eye refractive power of the eye to be inspected as well, by using the anterior segment cross-sectional image for obtaining the second state of the anterior segment, the measurement result can be obtained with high accuracy.

The third embodiment will be described below. The ophthalmologic apparatus of this embodiment is an apparatus capable of acquiring the axial length of an eye to be examined. For example, the ophthalmologic apparatus may have an optical system used for measuring the axial length, shape information obtaining means, axial length obtaining means, and the like. Also, for example, the ophthalmologic apparatus may have determination means, selection means, and the like.

<Eye refractive power measurement optical system>
The ophthalmologic apparatus of this embodiment may have an eye refractive power measurement optical system (for example, the measurement optical system 100). The eye refractive power measurement optical system is an optical system for acquiring the eye refractive power of the eye to be examined. For example, a configuration may be provided in which measurement light (first measurement light) is projected onto the fundus of the subject's eye, and the refractive power of the eye is obtained based on the reflected light of the measurement light reflected by the fundus. good. Note that the first measurement light may be visible light or infrared light.

The eye refractive power measuring optical system may be a measuring optical system used in an objective eye refractive power measuring device (autorefractometer, wavefront sensor, etc.). The projection optical axis of the first measurement light in the eye refractive power measurement optical system may be arranged on the plane of the light section formed by the cross-sectional image taking optical system, which will be described later. For this purpose, an eye refractive power measurement optical system is used to acquire the eye refractive power on the light-section plane of the anterior segment (surface eye refractive power). Of course, the eye refractive power measurement optical system may be capable of acquiring eye refractive power on other planes.

<Sectional imaging optical system>
The ophthalmologic apparatus of this embodiment may have a cross-sectional imaging optical system (for example, a cross-sectional imaging optical system). The cross-sectional image capturing optical system is an optical system for acquiring an anterior segment cross-sectional image of the subject's eye. For example, measuring light is projected toward the anterior segment of the eye to be inspected, and return light (scattered light) due to scattering of the measuring light is detected from an oblique direction with respect to the projection optical axis of the measuring light. A configuration for acquiring an eye cross-sectional image may be provided. Further, for example, the measurement light (second measurement light) is projected onto the anterior segment of the subject's eye to form a light section passing through the optical axis of the eye refractive power measurement optical system in the anterior segment, 2 A configuration for acquiring an anterior segment cross-sectional image based on scattered light from the light-section plane of the measurement light may be provided. The measurement light (second measurement light) may be visible light or infrared light.

The cross-sectional imaging optical system may be an optical system based on the Scheimpflug principle. In this case, the projection optical axis of the first measurement light in the eye refractive power measurement optical system and the projection optical axis of the second measurement light in the cross-sectional imaging optical system may be arranged coaxially. Further, in this case, the second measurement light may be projected as slit light in the cross-sectional imaging optical system. For example, the irradiation area of the slit light is set as the light cutting plane of the anterior segment. Further, in this case, the cross-sectional image capturing optical system may have a lens system and a photodetector arranged in a Scheimpflug relationship with the light section formed in the anterior segment. The light-receiving optical axis of the second measurement light is arranged so as to be inclined with respect to the light section plane.

In addition, it is preferable that the imaging range of the anterior segment cross-sectional image by the cross-sectional image capturing optical system includes from the front surface of the cornea to at least the front surface of the crystalline lens of the subject's eye. Needless to say, it is more preferable if the area from the anterior surface of the cornea to the posterior surface of the lens is included. In this case, since the corneal thickness, the anterior corneal curvature radius, the posterior corneal curvature radius, the anterior chamber depth, the lens thickness, the anterior lens curvature radius, and the posterior lens curvature radius can be obtained without omission, the axial length can be determined more appropriately. can ask.

<Shape Information Acquisition Means>
The ophthalmologic apparatus of this embodiment may include shape information acquisition means (for example, the control unit 50). The shape information acquiring means acquires shape information relating to the shape of the anterior segment, which includes a plurality of parameters, by analyzing the anterior segment cross-sectional image. For example, the shape information may be any information that can specify the shape of the translucent body included in the anterior segment. As an example, coordinates at which each transparent body is located, equations representing the shape of each transparent body, and values obtained from the equations (for example, curvature, thickness, depth, etc.), and the like may be used.

A plurality of parameters included in the shape information may include parameters related to the shape of the cornea. Examples include the radius of curvature of the anterior surface of the cornea, the radius of curvature of the posterior surface of the cornea, the corneal thickness, and the like. Also, the plurality of parameters may include parameters relating to the shape of the lens. For example, the radius of curvature of the anterior surface of the lens, the radius of curvature of the posterior surface of the lens, the thickness of the lens, and the like. Also, the plurality of parameters may include a parameter relating to the depth of the anterior segment. For example, an anterior chamber depth and the like can be mentioned.

Although it is desirable to obtain more parameters (in other words, measured values) of the translucent body from the anterior segment cross-sectional image analyzed by the shape information obtaining means, if the parameters cannot be obtained as an analysis result , if the parameters are not exact, etc. This can be caused, for example, by reflection of the subject's eyelids and eyelashes. Also, for example, it may change depending on the state of the anterior segment of the subject's eye (as an example, the state of the pupil, etc.). Due to these influences, effective parameters and ineffective parameters may coexist when an anterior segment cross-sectional image cannot be acquired appropriately. However, in the present embodiment, the axial length acquisition means (to be described later) obtains the axial length (second axial length) using the measured value of the effective parameter and the assumed value obtained by replacing the measured value of the ineffective parameter. By deriving , the axial length can be appropriately obtained. Of course, when the shape information acquisition means effectively obtains measured values of all parameters, it is also possible to derive the axial length (first axial length) using only each measured value.

<Axial Length Acquisition Means>
The ophthalmologic apparatus of the present embodiment may include axial length acquisition means (for example, control unit 50). For example, the axial length obtaining means may also serve as an image processing section, an axial length obtaining section, an arithmetic control section, and the like.

The eye axial length acquisition means may acquire the eye refractive power of the subject's eye by controlling acquisition of the eye refractive power using the eye refractive power measurement optical system. More specifically, by controlling the projection of the first measurement light in the eye refractive power measurement optical system and the detection by the photodetector of the fundus reflected light of the first measurement light, the eye refractive power of the subject's eye is measured. may be obtained.

Further, the axial length acquiring means may acquire the anterior segment cross-sectional image of the eye to be examined by controlling the acquisition of the anterior segment cross-sectional image using the cross-sectional image capturing optical system. More specifically, by controlling the projection of the second measurement light in the cross-sectional imaging optical system and the detection of the return light (scattered light) of the second measurement light by the photodetector, Partial cross-sectional images may be acquired.

It should be noted that the axial length acquisition means may acquire a plurality of anterior segment cross-sectional images by continuously projecting the second measurement light in the cross-sectional image capturing optical system. In this case, the eye axial length acquisition means executes the projection of the second measurement light and the detection of the return light in real time, and captures the anterior segment cross-sectional images as a moving image to obtain a plurality of anterior segment cross-sectional images. Images may be acquired. Further, in this case, the measuring means executes projection of the second measurement light and detection of the return light at predetermined time intervals (for example, at intervals of 1 second, etc.), and the anterior segment cross-sectional image is stilled. A plurality of anterior segment cross-sectional images may be obtained by capturing images.

The axial length acquisition means acquires the axial length of the eye to be examined based on the refractive power of the eye and a plurality of parameters included in the shape information acquired by the shape information acquisition means by analyzing the cross-sectional image of the anterior segment of the eye. You may The axial length acquired by the axial length acquiring means may include, as the plurality of parameters, a first axial length derived using each measurement value. That is, a first axial length derived without using hypothetical values that replaced each measurement may be included. In addition, the axial length may include, as a plurality of parameters, a second axial length that is partially derived using assumed values. That is, a second axial length derived using measurements and hypotheses may be included. The axial length obtaining means derives one or both of the first axial length and the second axial length based on an operation signal input by the examiner's operation of the operating means (for example, the monitor 16). You can choose either Further, it may be selected whether to derive one or both of the first axial length and the second axial length based on the selection result of the selection means, which will be described later.

For example, the axial length acquisition means may change some of the parameters in the shape information acquired by the shape information acquisition means, which are not valid, from measured values to assumed values. For example, the hypothetical value may be a standard value adopted by a predetermined eye optical model (for example, the Gullstrand model eye, etc.). Moreover, the average value based on the statistical data etc. regarding eyes may be used. Alternatively, it may be an estimated value that can be obtained by taking into consideration the measured value of an effective parameter and the general ratio of the corneal anterior surface and the lens anterior surface in the eye. Alternatively, the measured value of the subject's eye obtained in the past by at least one of an ophthalmic device and a device different from the ophthalmic device may be used. A plurality of standard values and average values may be prepared for at least one of age, sex, region, etc., and the examiner can select based on which value the axial length is calculated. good.

For example, the axial length acquisition means may acquire the axial length based on the refractive power of the eye and a plurality of parameters. For example, the eye axial length may be derived by ray tracing calculations based on the eye refractive power and a plurality of parameters. In the ray tracing calculation, the distance between the point of intersection and the vertex of the cornea when a light ray incident on a predetermined position of the anterior segment from the far point is refracted by the translucent body and intersects the optical axis is derived as the axial length of the eye. be. At this time, instead of the equivalent spherical power that is generally used when specifying the far point in the field of ophthalmology, the eye refractive power at the light-section plane (surface eye refractive power) may be used. As a result, the position of the far point of the light ray passing through the cut plane can be specified more properly. As a result, the axial length can be obtained more appropriately. At this time, a ray tracing calculation may be performed for each of the plurality of rays, and the axial length of the eye may be obtained as a result of the ray tracing calculation for each ray. For example, an average value (or a weighted average) of the axial lengths obtained by each ray tracing calculation may be obtained as the axial length of the subject's eye.

In the ray tracing calculation, the incident position of the ray with respect to the boundary surface of each transparent body and the angle change at the boundary surface are determined by considering the shape of the transparent body at the cut plane specified from the anterior segment information. may be The ray tracing calculation may also take into account the decentration of the anterior segment translucent body. Eccentricity is identified based on the anterior segment information. As a result of considering the eccentricity of the transmissive body in the cut plane, the axial length can be obtained more appropriately. In this case, for example, a ray tracing calculation is performed for each of a plurality of rays including at least the first ray and the second ray to obtain the axial length for each ray, and based on the plurality of axial lengths, the final measurements may be obtained. The first light ray and the second light ray are light rays arranged on the cutting plane with the eye axis interposed therebetween.

In the present embodiment, the axial length acquisition means may adjust the light amount of the second measurement light in the cross-sectional image capturing optical system based on the anterior segment cross-sectional image. More specifically, an anterior segment cross-sectional image (first anterior segment cross-sectional image) of the eye to be inspected is acquired, and if this anterior segment cross-sectional image is determined to be inappropriate for analysis, the amount of light of the second measurement light is reduced. After adjustment, the anterior segment cross-sectional image (second anterior segment cross-sectional image) may be acquired again. Further, in the present embodiment, the axial length acquisition means may adjust the detection conditions of the photodetector in the cross-sectional image capturing optical system based on the anterior segment cross-sectional image. More specifically, when the first anterior segment cross-sectional image is acquired and the first anterior segment cross-sectional image is determined to be inappropriate for analysis, the detection conditions of the photodetector are adjusted to obtain the second anterior segment cross-sectional image. A cross-sectional image may be acquired. This increases the possibility of obtaining appropriate values for the plurality of parameters based on the anterior segment cross-sectional image, and as a result improves the accuracy of the axial length.

For example, the axial length acquisition means adjusts the light amount of the second measurement light within a predetermined range in which the luminance information of each translucent body detected from the second anterior segment cross-sectional image is not saturated. good. In this case, the axial length acquisition means may increase or decrease the set value of the output of the light source, or insert or remove the optical member in the optical path of the second measurement light projected from the light source. As an example, the predetermined range may be set in advance based on the detection sensitivity, gain, etc. of the photodetector. Further, for example, the axial length acquisition means adjusts the detection conditions of the photodetector within a predetermined range in which the luminance information of each translucent body detected from the second anterior segment cross-sectional image is not saturated. may In this case, the axial length acquisition means may change at least one of the exposure time, gain, etc. of the photodetector.

The eye axial length acquisition means may acquire the eye refractive power and acquire the anterior segment cross-sectional image in parallel. In this case, the acquisition means obtains the detection timing of the photodetector of the eye refractive power measurement optical system and the light of the cross-sectional image taking optical system in a state in which measurement light is projected from both optical systems onto the eye to be examined. The detection timing of the detector may be the same timing (in parallel). Note that the term "same" as used herein does not necessarily mean that the respective detection timings are exactly the same. For example, there may be a time difference that does not cause a significant difference in the state of the subject's eye (pupil state or accommodative state) between the respective detection timings.

In the present embodiment, the eye axial length acquisition means may control the eye refractive power measurement optical system and the cross-sectional image capturing optical system, and acquire the eye refractive power and the cross-sectional image in a state where fog is added to the subject's eye. . Further, the first axial length and the second axial length may be obtained based on the anterior segment cross-sectional image obtained with fog added to the subject's eye. As a result, each parameter can be acquired from an anterior segment cross-sectional image obtained by setting the anterior segment of the subject's eye in an appropriate state (that is, in a state in which accommodation is canceled by fogging). Furthermore, if there are parameters that are not effective as measured values, by replacing them with hypothetical values, the axial length can be derived satisfactorily.

<Determination means>
The ophthalmologic apparatus of this embodiment may include determination means (for example, the control unit 50). The determining means may determine the quality of at least one of the plurality of parameters based on the anterior segment cross-sectional image. For example, the determining means may determine whether the parameter is good or bad by determining whether the anterior segment cross-sectional image is suitable for analysis. That is, if the anterior segment cross-sectional image is inappropriate, the parameter may be considered unsatisfactory without obtaining a measured value. Further, for example, the determining means may determine the quality of the parameters by determining whether the measured values of the parameters based on the anterior segment cross-sectional image are appropriate. This makes it easier to obtain appropriate values even when measured values for multiple parameters are unavailable or inaccurate.

For example, the determining means may determine the quality of at least one of the plurality of parameters based on whether or not the subject's eyelids and eyelashes are reflected in the anterior segment cross-sectional image. Further, for example, the determining means may determine the quality of at least one of the plurality of parameters based on the detection width in the horizontal direction of each translucent body in the anterior segment cross-sectional image. Further, for example, the determination means may determine the quality of at least one of the plurality of parameters based on the pupil information of the subject's eye. Of course, the quality of at least one of a plurality of parameters may be determined from these combinations.

It should be noted that the pupillary condition of the eye to be examined may be any information that allows the presence or absence of miosis and mydriasis to be grasped. For example, a pupil diameter, or a determination result obtained by determining the presence or absence of miosis or mydriasis based on the pupil diameter, or the like may be used. In this case, whether or not the measured values of a plurality of parameters can be considered valid may be associated with the pupil information. As an example, a value effective as a measurement value may be selected from a plurality of parameters according to the presence or absence of miosis or mydriasis. Also, as an example, a value that is effective as a measurement value may be selected from a plurality of parameters according to the degree of miosis or mydriasis.

In the present embodiment, the determination means may determine the quality of at least one of the parameters included in the shape information of the anterior segment based on the luminance information of the anterior segment cross-sectional image. For example, the quality of a plurality of parameters may be determined using changes in luminance information in an anterior segment cross-sectional image. The luminance information may be information represented by at least one of luminance, gradation, gradation, and the like. Thus, whether or not the measured values of the parameters are effective can be easily grasped by considering the presence or absence of blinking of the subject's eye, the presence or degree of miosis, and the like.

Further, in the present embodiment, the determining means may determine the quality of at least one of the plurality of parameters based on the evaluation information for evaluating the reliability of the plurality of parameters included in the shape information of the anterior segment. good. The reliability of a plurality of parameters is sufficient if it is possible to express whether or not the measured values as parameters in each translucent body have been properly acquired.

For example, such reliability may be obtained based on the luminance information of the anterior segment cross-sectional image. In this case, as an example, at least one of the presence or absence of reflection of the eyelids and eyelashes, the state of the pupil, the detection width in the horizontal direction of each translucent body in the cross-sectional image of the anterior segment, etc. is acquired as information representing reliability. You may Also, for example, such reliability may be obtained based on information different from the luminance information of the anterior segment cross-sectional image. In this case, as an example, the alignment relationship between the subject's eye and the cross-sectional imaging optical system may be acquired as information representing reliability.

Note that the evaluation information for evaluating reliability may be acquired as evaluation symbols, evaluation values, and the like. The evaluation information may be information that is polarized depending on whether or not it is reliable, or may be information that is graded according to the degree of reliability.

For example, the determination means may acquire the evaluation information by using a correspondence table that associates the evaluation information acquired by each translucent body with the quality of the parameters. Further, for example, the determination means may acquire the evaluation information by using an arithmetic expression in which the evaluation information acquired by each translucent body and the quality of the parameters are associated with each other. The correspondence table and the coefficients of the arithmetic formula may be set in advance from experiments, simulations, or the like.

In the present embodiment, the determining means may determine the quality of each parameter when there is a plurality of pieces of shape information for each anterior segment cross-sectional image. The judging means may judge the quality of each parameter obtained for each transparent body, or may average the parameters obtained for each transparent body and judge the quality. In this case, the determination means may exclude images having outliers from the plurality of anterior segment cross-sectional images, and determine the quality of the parameters for the remaining anterior segment cross-sectional images. For example, the anterior segment cross-sectional image having an outlier may be an image from which a plurality of parameters included in the shape information of the anterior segment cannot be obtained. As an example, at least one of an image in which a part of the translucent body is missing due to blinking or miosis of the subject's eye, an image in which the detection width of the translucent body in the horizontal direction is short, a dark image in which the overall luminance information is insufficient, etc. or For example, these anterior segment cross-sectional images may be excluded by statistical processing. This further improves the accuracy of the axial length.

<Selection means>
The ophthalmologic apparatus of the present embodiment may include selection means (for example, control unit 50). The selection means may select derivation of at least one of the first axial length and the second axial length based on the determination result of the determination means. For example, the selection means may select derivation of the first axial length and the second axial length based on the quality of a plurality of parameters corresponding to one anterior segment cross-sectional image. Further, for example, derivation of the first axial length and the second axial length may be selected based on the quality of a plurality of parameters corresponding to each of the plurality of anterior segment cross-sectional images. Therefore, even when an appropriate anterior segment cross-sectional image cannot be obtained due to the blinking or miosis of the subject's eye, it is easy to obtain an accurate axial length.

<Output means>
The ophthalmologic apparatus of this embodiment may include output means (for example, the control unit 50). The output means may output intraocular dimension information. Of course, the output means may output the eye refractive power, the cross-sectional image of the anterior segment, the evaluation information, etc. together with the intraocular dimension information.

For example, the output means may function as display control means and cause the intraocular dimension information to be displayed on the display means (for example, the monitor 16). Further, for example, the output means may function as print control means and cause a print means (for example, a printer) to print the intraocular dimension information. Further, for example, the output means may function as a communication means and store the intraocular dimension information in a storage means (for example, a memory or a server). The output means may output the intraocular dimension information in at least one of these output forms.

For example, the intraocular dimension information may be the axial length of the eye. Further, for example, the intraocular dimension information is shape information of the anterior segment (that is, at least one of the curvature radius of the anterior and posterior surface of the cornea, the corneal thickness, the curvature radius of the anterior and posterior surface of the lens, the thickness of the lens, the depth of the anterior chamber, etc.). may be The intraocular dimension information output by the output means may include first dimension information obtained based on the measured values of the parameters in the shape information of the anterior segment. For example, this includes the first axial length. In addition, the intraocular dimension information may include second dimension information acquired based on the measured values and assumed values of the parameters in the shape information of the anterior segment. For example, this includes the second axial length.

The output means may output the first dimension information and the second dimension information as the intraocular dimension information in a distinguishable manner. More specifically, first dimensional information derived based only on measured values of multiple parameters and second dimensional information derived based on measured values and assumed values of multiple parameters are output in a distinguishable manner. may

The output means outputs a temporal change of the intraocular dimension information (at least one of the first dimension information and the second dimension information) when there is intraocular dimension information acquired in the past for the eye to be examined. may That is, using two or more pieces of dimensional information obtained on different dates, changes over time may be output. The change over time of the intraocular dimension information may be output as information in which the dimension information is summarized for each time series. For example, it may be output as a table or graph. As a result, it becomes easier to grasp the tendency that accompanies the change over time, the follow-up observation is efficiently performed, and the progress of myopia based on the axial length of the eye can be easily evaluated.

<Example>
An example of an ophthalmologic apparatus according to this embodiment will be described.

<Overall composition>
FIG. 1 is an external view of an ophthalmologic apparatus 10. FIG. The ophthalmologic apparatus 10 is a multi-function machine of an objective eye refractive power measuring apparatus (especially an autorefractometer in this embodiment) and a Scheimpflug camera. In this embodiment, the ophthalmologic apparatus 10 is a stationary examination apparatus, but is not necessarily limited to this, and may be hand-held.

The ophthalmologic apparatus 10 has at least a measurement unit 11 , a base 12 , an alignment drive section 13 , a face support unit 15 , a monitor 16 and an arithmetic control section 50 .

The measurement unit 11 includes a measurement system, an imaging system, and the like used for examination of an eye to be examined. In this embodiment, the optical system shown in FIG. 2 is arranged.

The alignment drive section 13 may be able to move the measurement unit 11 three-dimensionally with respect to the base 12 .

The face support unit 15 is used to fix the subject's face in front of the measurement unit 11 . The face support unit 15 is fixed to the base 12 and supports the subject's face.

The monitor 16 functions as a touch panel that also serves as an operation unit. In addition, the monitor 16 displays the ocular refractive power of the subject's eye E, the anterior segment cross-sectional image, the ocular axial length, and the like on the screen.

The arithmetic control unit 50 (also referred to as a processor; hereinafter simply referred to as the control unit 50 ) controls the entire ophthalmologic apparatus 10 . It also processes various inspection results acquired via the measurement unit 11 .

<Optical system>
FIG. 2 is a schematic diagram showing the optical system of the ophthalmologic apparatus 10. As shown in FIG. As an example, the ophthalmologic apparatus 10 includes a measurement optical system 100, a fixation target presentation optical system 150, a front imaging optical system 200, a cross-sectional imaging optical system (an irradiation optical system 300a and a light receiving optical system 300b, an index projection optical system 400, and It has an alignment target projection optical system, and half mirrors 501, 502, 503 for branching and combining the optical paths of each optical system, an objective lens 505, etc. In each optical system, the light source side is upstream, The side of the eye to be examined is the downstream side.

<Measurement optical system>
The measurement optical system 100 is used to objectively measure the eye refractive power of the eye E to be examined. For example, each value of SPH: spherical power, CYL: cylindrical power, and AXIS: cylinder axis angle may be obtained as a measurement result of the eye refractive power.

The measurement optical system 100 has a projection optical system 100a and a light receiving optical system 100b.

The projection optical system 100a has at least a measurement light source 111, and projects a spot-shaped measurement light onto the fundus of the eye E to be inspected via the center of the pupil or the corneal vertex of the eye E to be inspected. The measurement light source 111 may be an SLD light source, an LED light source, or other light sources. In this embodiment, infrared light is used as the measurement light. For example, near-infrared light with a peak wavelength between 800 nm and 900 nm may be used. As an example, near-infrared light with a peak wavelength of 870 nm may be used.

In this embodiment, a prism 115 is arranged on the common path of the projection optical system 100a and the light receiving optical system 100b. By rotating the prism 115 around the optical axis, the projection light flux on the pupil is rotated eccentrically at high speed. As an example, in this embodiment, the projection light flux is eccentrically rotated in a region of φ2 mm to φ4 mm on the pupil. This area is the eye refractive power measurement area in this embodiment.

The light receiving optical system 100b has at least a ring lens 124 and an imaging element 125. The light-receiving optical system 100b takes out the reflected light flux of the measurement light flux reflected from the fundus in a ring shape through the periphery of the pupil. The ring lens 124 is arranged at a pupil conjugate position, and the imaging device 125 is arranged at a fundus conjugate position. By analyzing the ring image formed on the image sensor 125 via the ring lens 124, the eye refractive power is derived.

As described above, in this embodiment, the measurement light is eccentrically rotated at high speed on the pupil. Analysis processing is performed on an added image of image data that is sequentially output, and an eye refractive power is derived. In this embodiment, at least values of SPH: spherical power, CYL: cylindrical power, and AXIS: cylinder axis angle are acquired as a result of the analysis processing. 

In addition to the measurement light source 111, the prism 115, the ring lens 124, and the imaging element 125, the measurement optical system 100 may have optical elements such as lenses and diaphragms. The measurement light flux from the measurement light source 111 passes through the hole portion of the hole mirror 113 and the prism 115, is reflected by the half mirrors 502 and 501, respectively, becomes coaxial with the optical axis L1, and passes through the objective lens 505. and reach the fundus. A reflected light flux, which is the measurement light flux reflected by the fundus, passes through the optical path through which the measurement light flux has passed, is reflected by the mirror portion of the hole mirror 123 , and reaches the imaging device 125 via the ring lens 124 .

<Fixation target presentation optical system>
A fixation target presenting optical system 150 presents a fixation target to the eye E to be examined. A fixation target is presented on the optical axis of the measurement optical system 100 . The fixation target presenting optical system 150 is used to fixate the eye E to be examined. It is also used to apply fogging and accommodation load to the subject's eye.

For example, the fixation target presenting optical system 150 includes at least a light source 151 and a fixation target plate 155 . The fixation target plate 155 may be placed at a fundus conjugate position. A fixation light flux from the light source 151 passes through the half mirror 503 after passing through the fixation target plate 155 and the lens 156 on the optical axis L2. Further, the light passes through the lens 504, passes through the half mirror 502, and is reflected by the half mirror 501, so that the light becomes coaxial with the optical axis L1. The fixation luminous flux further passes through the objective lens 505 and reaches the fundus.

The measurement light source 111, the ring lens 124, and the imaging element 125 in the measurement optical system 100, and the light source 151 and the fixation target plate 155 in the fixation target presentation optical system 150 are driven by the drive unit 161 as a drive unit 160. It is integrally movable along the . For example, the focal length within the driving unit 160 in the measurement optical system 100 and the focal length within the driving unit 160 in the fixation target presenting optical system 150 have a predetermined relationship. For example, by moving the drive unit according to the eye refractive power of the eye E to be examined, the presentation distance of the fixation target plate 155 to the eye E (that is, the presentation position of the fixation target) can be changed. 111 and the imaging device 125 are optically conjugated to the fundus. At this time, regardless of the movement of the drive unit, the hole mirror 113 and the ring lens 124 are pupil conjugate at a constant magnification.

<Front view optical system>
The front imaging optical system 200 is used to capture a front image of the anterior segment of the eye E to be examined. For example, the front imaging optical system 200 includes an imaging element 205 and the like. The imaging element 205 may be arranged at a pupil conjugate position. As the front image, an observation image of the anterior segment may be acquired. The observed image is used for alignment and the like. Also, the index image (point image) projected onto the cornea from the index projection optical system 400 and the index image (Meyerling image) projected onto the cornea from the alignment index projection optical system 600 are photographed by the front imaging optical system 200. be done.

<Section imaging optical system>
The cross-sectional imaging optical system is used to capture a cross-sectional image of the anterior segment of the eye. The cross-sectional imaging optical system includes an irradiation optical system 300a and a light receiving optical system 300b.

The irradiation optical system 300a is coaxial with the projection optical axis (optical axis L1) of the measurement light in the measurement optical system 100, and irradiates the anterior segment with slit light. The irradiation optical system 300a has a light source 311, a slit 312, and the like. The light source 311 may be an SLD light source, an LED light source, or other light sources. In this embodiment, red visible light or near-infrared light is used as illumination light. For example, red visible light or near-infrared light with peak wavelengths between 650 nm and 800 nm may be utilized. As an example, red visible light with a peak wavelength of 730 nm may be used. Of course, near-infrared light with a predetermined wavelength as a peak wavelength may also be used. The slit 312 may be placed at a pupil conjugate position.

The light source 311 of the irradiation optical system 300a will be described in detail. FIG. 3 is a schematic diagram showing the relationship between the visual sensitivity of an eye to be inspected and the wavelength. The eye to be inspected has luminosity in the visible range, which generally peaks around 550 nm, which is green visible light, and gradually decreases as the wavelength increases (closer to the infrared range). In other words, the subject's eye is likely to feel dazzling in green visible light, and less likely to feel dazzling in red visible light. It is said that infrared light is not dazzling.

Conventionally, blue visible light, green visible light, white visible light, etc. have been used as illumination light when acquiring cross-sectional images of the anterior segment based on the Scheimpflug principle. This is because a cataract or the like is likely to appear in a cross-sectional image due to the influence of the transmittance of the subject's eye. On the other hand, as the prevalence of myopia has increased in recent years, mainly among young people, the measurement of axial length in young people has been emphasized. It is also possible to use a different light as illumination light.

Therefore, in this embodiment, red visible light to near-infrared light, which is less likely to be perceived by the eye to be examined, is used as illumination light. For example, the visibility around 650 nm, which is red visible light, drops to about 1/10, and the visibility around 700 nm drops to about 1/200, relative to the visibility around 550 nm, which is green visible light. Therefore, the burden on the subject is greatly reduced. In particular, when targeting young people including children, the burden is reduced and the efficiency of measurement is improved.

In this embodiment, the passage cross section of the slit light in the anterior segment is referred to as a "cut plane". The cut plane becomes the object plane of the cross-section imaging optical system. In FIG. 2, the opening of the slit 312 has a horizontal direction (the depth direction of the paper surface) as its longitudinal direction. Therefore, in this embodiment, the horizontal plane (XZ section) including the optical axis L1 is set as the cutting plane. In this embodiment, a cut surface is formed at least between the anterior corneal surface and the posterior surface of the lens.

The light receiving optical system 300b has a lens system 322, an imaging device 321, and the like. In the light-receiving optical system 300b, the lens system 322 and the imaging device 321 are arranged in a Scheimpflug relationship with the cutting plane set in the anterior segment. That is, the optical arrangement is such that the extended planes of the cut plane, the principal plane of the lens system 322, and the imaging surface of the imaging element 321 intersect at one line of intersection (one axis). A cross-sectional image of the anterior segment is acquired based on the signal from the imaging device 321 . The imaging element 321 may be configured with a semiconductor substrate made of silicon as a single element.

The imaging element 321 of the light receiving optical system 300b will be described in detail. FIG. 4 is a schematic diagram showing the relationship between the light receiving sensitivity of the image sensor 321 and the wavelength. For example, an imaging device using silicon as a single element has sensitivity to wavelengths in the vicinity of 300 nm to 1000 nm, including wavelengths in the ultraviolet, visible, and infrared regions, but has sensitivity in the vicinity of 550 nm to 650 nm, which includes green visible light. It becomes the maximum, and gradually decreases as it approaches the infrared region. However, the sensitivity of 650 nm or more, which includes red visible light to near-infrared light, used in the irradiation optical system 300a is sufficient for obtaining a cross-sectional image of the anterior segment.

It should be noted that, for example, some imaging devices have the highest sensitivity in the infrared region, but they are expensive. While it is desired that the device be widely used in many facilities such as hospitals and schools, the high cost of the device may hinder the widespread use of the device. If an imaging element made of silicon is used, the cost of the device can be reduced.

In such a cross-sectional imaging optical system, the measurement light flux from the light source 311 passes through the slit 312 on the optical axis L3 and becomes a slit light flux. Coaxial with L2. Further, the light passes through the lens 504, passes through the half mirror 502, and is reflected by the half mirror 501, so that the light becomes coaxial with the optical axis L1. The measurement light flux further passes through the objective lens 505 and reaches the anterior segment of the eye. Return light from the cut surface formed in the anterior segment reaches the imaging device 321 via the lens 322 .

<Target projection optical system>
A target projection optical system 400 is used to measure the corneal shape. The target projection optical system 400 projects a target for measuring the shape of the cornea from the front facing the subject's eye to the anterior segment of the eye.

A target projection optical system 400 includes a plurality of point light sources 401 . The point light source 401 projects an infinity index by irradiating the cornea with parallel light. The point light source 401 emits infrared light. However, it may be visible light. The point light sources 401 are arranged vertically and horizontally symmetrically about the optical axis L1. For example, in this embodiment, two point light sources are provided on each side. This projects four point image indices onto the cornea. Note that the shape of the index is not limited to this, and a linear index or the like may be included. Also, the number of indices is not limited to this, and may be composed of three or more point image indices.

In this embodiment, the circumferential area onto which these four point images are projected is the corneal shape measurement area by the index projection optical system 400 and the front imaging optical system 200 . As an example, when a corneal model eye having a predetermined radius of curvature is placed at a predetermined working distance, each point image is projected onto a φ3 mm circumferential region of the corneal model eye.

<Alignment target projection optical system>
The alignment target projection optical system is used to align (align) the measurement unit 11 with the eye E to be examined. In this embodiment, the alignment light source 601 and the index projection optical system 400 form an alignment index projection optical system. For example, the working distance is adjusted by moving the measurement unit 11 in the front-rear direction so that the Purkinje image by the alignment light source 601 and the Purkinje image by the index projection optical system 400 are photographed at a predetermined ratio. may

The alignment light source 601 projects a finite distance index by irradiating the cornea with diffused light. The alignment light source 601 emits infrared light. However, it may be visible light. The alignment light source 601 is arranged in a ring shape around the optical axis L1. Thereby, in this embodiment, a ring index (so-called Mayer ring) is projected onto the cornea.

<Common optical path for fixation target presentation optical system and cross-section imaging optical system>
In this embodiment, both the fixation target presenting optical system 150 and the target projecting optical system 300a are irradiated with visible light. A half mirror 503 makes the optical axis L2 of the fixation target presenting optical system 150 and the optical axis L3 of the target projecting optical system 300a coaxial. By arranging the fixation target presenting optical system 150 on the transmission side of the half mirror 503 and the target projection optical system 300a on the reflection side of the half mirror 503, the respective optical paths are shared. For example, the half mirror 503 is of a flat type, and astigmatism tends to occur on the transmission side of the half mirror 503 . The optotype projection optical system 300a requires a certain imaging performance in order to obtain a clear cross-sectional image 70 by forming a cross section in the anterior segment. For this reason, it is preferable that the target projection optical system 300a be arranged on the reflection side, which is less affected by astigmatism.

Also, in this embodiment, a lens 504 a is arranged on the optical axis of the fixation target presenting optical system 150 . The lens 504 a functions as a total length shortening lens for shortening the overall length of the fixation target presenting optical system 150 . The lens 504a also serves to reduce the diameter of the lens 156 located upstream of the lens 504a.

FIG. 5 is a schematic diagram in which the fixation target presenting optical system 150 is simplified. The upper diagram of FIG. 5 shows the case where the lens 504a is not arranged. The lower diagram of FIG. 5 shows a case where the lens 504a is arranged. Here, the optical path from the subject's eye E to the fixation target plate 155 is a straight line, and some optical members are omitted. Fundus imaging rays from the center and periphery of the fixation target plate 155 are represented by solid and dotted lines, respectively.

When the distance from the subject's eye E to the objective lens is set to a predetermined working distance, in the upper diagram of FIG. . Light rays from the central portion and the peripheral portion of the fixation target plate 155 both reach the lens 156 with large diameters. On the other hand, when a lens 504a is arranged in the fixation target presenting optical system 150 as shown in the lower diagram of FIG. 5, the distance of the fixation target presenting optical system 150 can be shortened. Each ray from fixation target plate 155 reaches lens 156 with a small diameter.

Note that, for example, the fixation target presenting optical system 150 may be a target-side telecentric optical system, and the lens 504a may be arranged at a pupil conjugate position. At this time, light rays from the center and peripheral portions of the fixation target plate 155 pass through the center of the lens 504a, so that the overall focal length (composite focal length) of the fixation target presenting optical system 150 changes. do not do. Therefore, the relationship between the focal lengths of the fixation target presenting optical system 150 and the measuring optical system 100 in the drive unit 160 is maintained.

By arranging the lens 504a in the fixation target presenting optical system 150 in this manner, the lens 156 can be designed with a small diameter. Further, the total length of the fixation target presenting optical system 150 can be shortened while maintaining the predetermined working distance of the subject's eye E and the synthetic focal length of the fixation target presenting optical system 150 . As a result, the size of the ophthalmologic apparatus 10 can be reduced.

Also, in this embodiment, a lens 504b is arranged on the optical axis of the target projection optical system 300a. The lens 504b has a role of reducing the diameter of the objective lens 505 located downstream of the lens 504b.

FIG. 6 is a simplified schematic diagram of the optotype projection optical system 300a. The upper diagram of FIG. 6 shows the case where the lens 504b is not arranged. The lower diagram of FIG. 6 shows a case where the lens 504b is arranged. Here, the optical path from the subject's eye E to the slit 312 is a straight line, and some optical members are omitted. Pupil imaging rays from the center and periphery of the slit 312 are represented by solid and dotted lines, respectively.

In the upper diagram of FIG. 6 and the lower diagram of FIG. 6, light rays from the center of the slit 312 pass through the center of the objective lens 505 regardless of the presence or absence of the lens 504b. However, in the top view of FIG. 6, rays from the periphery of slit 312 are refracted at positions further away from the center of objective lens 505 . In order to allow such rays to reach the subject's eye E, an objective lens 505 with a large diameter is required. On the other hand, in the lower diagram of FIG. 6 , light rays from the periphery of the slit 312 are refracted at the center position of the objective lens 505 . A small diameter objective lens 505 can be used to allow such rays to reach the eye E to be examined.

By arranging the lens 504b in the target projection optical system 300a in this way, the objective lens 155 can be designed with a small diameter. It should be noted that the rays from the central and peripheral portions of the slit 312 are refracted in a region farther from the center of the objective lens 505, and the greater the aberration may occur. Therefore, an objective lens 155 having an appropriate diameter may be used so as to reduce the size of the ophthalmologic apparatus 10 and suppress the occurrence of aberrations.

Note that, in this embodiment, a lens 504 that shares the above-described lenses 504a and 504b having different roles is arranged in the fixation target presenting optical system 150 and the target projecting optical system 300a. For example, the lens 504 is arranged downstream of the half mirror 503 where the optical axis L2 of the fixation target presenting optical system 150 and the optical axis L3 of the target projecting optical system 300a are combined. As a result, the inside of the optical system can be made more space-saving.

<Control operation>
A control operation of the ophthalmologic apparatus 10 will be described with reference to an example of the flowchart shown in FIG. In this embodiment, the ophthalmologic apparatus 10 sequentially performs corneal curvature measurement, eye refractive power measurement, and photographing of an anterior segment cross-sectional image, and the axial length is obtained based on the results of the measurements and photographing. be.

<Alignment (S1)>
First, alignment of the measurement unit 11 with respect to the eye E to be examined is performed. The examiner instructs the subject to put his/her face on the face support unit 15 . The control unit 50 starts presentation of the fixation target and acquisition of the anterior segment observation image.

For example, the control unit 50 adjusts the subject's eye E and the ophthalmologic apparatus 10 to a predetermined positional relationship based at least on the observed image of the anterior segment acquired via the front imaging optical system 200 . More specifically, alignment in the XY directions is performed so that the optical axis L1 coincides with the corneal vertex of the eye E to be examined. Alignment in the Z direction is also performed so that the distance between the subject's eye E and the ophthalmologic apparatus 10 is a predetermined working distance. At this time, an alignment index may be projected onto the cornea and the alignment may be adjusted based on the alignment index detected in the observed image.

<Corneal shape measurement (S2)>
Next, the corneal shape of the subject's eye E is measured. The control unit 50 projects a point image index from the index projection optical system 400 and captures a corneal Purkinje image of the point image index using the front imaging optical system 200 . The control unit 50 also acquires corneal shape information based on the corneal Purkinje image. For example, the corneal shape information is derived based on the image height of the corneal Purkinje image. In this embodiment, at least each value of the corneal curvature, the astigmatic power, and the astigmatic axis angle is acquired as the corneal shape information.

<Eye refractive power measurement (S3)>
Next, the ocular refractive power of the subject's eye E is measured. For example, in eye refractive power measurement, preliminary measurement may be performed first, and main measurement may be performed later.

In the preliminary measurement, the ocular refractive power of the subject's eye E is measured with the fixation target placed at a predetermined presentation distance. At the time of measurement, the fixation target plate 155 may be arranged at an initial position that is optically sufficiently far away from the subject's eye E and that corresponds to the far point of the 0D eye. A ring image captured by the imaging device 125 based on the measurement light irradiated in this state is image-analyzed by the control unit 50 . As an analysis result, the refractive power value in each meridian direction is obtained. At least the spherical power in the preliminary measurement is obtained by subjecting the refractive power in each meridional direction to a predetermined process.

Subsequently, the control unit 50 moves the fixation target plate 155 to the fog start position where the subject's eye E is in focus, according to the pre-measured spherical power of the subject's eye. As a result, the eye E to be examined can clearly observe the fixation target. Thereafter, the control unit 50 adds fog to the subject's eye E by moving the fixation target from the fog start position. This cancels the adjustment of the eye E to be examined. In addition, miosis occurs at the same time when the eye to be examined is in the state of accommodation, but as accommodation is canceled due to fog, the pupil is not in the state of miosis.

The main measurement is performed with fog added to the subject's eye E. By performing a predetermined analysis process on the ring image captured for the eye E to which fog is added, the SPH of the eye E to be examined: spherical power, CYL: cylindrical power, AXIS: astigmatism axis angle objective value is retrieved.

In the eye refractive power measurement, since infrared light is projected onto the subject's eye E as measurement light, the pupil diameter of the subject's eye E is a predetermined size in which miosis (for example, φ2 mm or less) is suppressed. As an example, it is any diameter included in the measurement area of the subject's eye E (area of φ2 mm to φ4 mm on the pupil).

<Capturing an anterior segment cross-sectional image (S4)>
Next, a cross-sectional image (Scheimpflug image) of the anterior segment of the subject's eye E is captured. Immediately after completing the main measurement of the eye refractive power, the control unit 50 captures a cross-sectional image of the anterior segment of the eye. For example, the operation of capturing a cross-sectional image may be performed using the completion of the main measurement of the eye refractive power as a trigger. That is, immediately after the completion of the main measurement, illumination light is emitted from the illumination optical system 300a, and the scattered light scattered by the cornea and lens is imaged on the imaging device 321 to form an image of the cross section of the anterior segment. Get an image. This reduces misalignment between the measurement of the eye refractive power and the imaging of the cross-sectional image.

<Axial Length Calculation (S5)>
Next, the axial length of the eye E to be examined is calculated. The control unit 50 calculates the axial length based on the information or images acquired in steps S2 to S4.

First, the control unit 50 obtains the position of the far point FP (see FIG. 9) with respect to the corneal vertex C based on the measurement result of the eye refractive power of the eye E to be examined. For example, if the subject's eye E has no astigmatism, SPH=−5D, and VD=12 mm, the distance from the corneal vertex C to the far point FP is 12+1000/5=212 mm. Light rays from the far point FP are considered to be imaged on the fundus. Note that VD=12 mm is a constant value indicating the distance between the corneal vertices on the premise of wearing spectacle lenses. VD may vary from device to device.

FIG. 8 is an example of a cross-sectional image 70 of the anterior segment. Subsequently, based on the cross-sectional image 70 of the anterior segment of the eye E to be examined, the control unit 50 acquires anterior segment shape information regarding the shape of the anterior segment. For example, the anterior segment shape information includes the radius of curvature of the anterior corneal surface (Ra), the radius of curvature of the posterior corneal surface (Rp), the corneal thickness (CT), the depth of the anterior chamber (ACD), the radius of curvature of the anterior lens surface (ra), Information such as the radius of curvature of the posterior lens surface (rp), lens thickness (LT), etc. may be included. The information acquired in step S2 can also be used as the anterior segment shape information.

The control unit 50 performs image processing on the cross-sectional image 70 to detect each translucent body (for example, the cornea, aqueous humor, lens, etc.) and acquire anterior segment shape information. For example, luminance information of the cross-sectional image 70 may be used to detect pixel positions corresponding to tissue boundaries (corneal anterior and posterior surfaces, lens anterior and posterior surfaces, irises, etc.), and information such as curvature radii may be obtained. Further, for example, the distance between the pixel positions corresponding to the boundary of the tissue may be obtained, and information such as the thickness and depth of the tissue may be acquired.

FIG. 9 is a schematic diagram for explaining the method of deriving the axial length of the eye. In this embodiment, the axial length may be derived based on the ray tracing calculation on the cut plane of the anterior segment. For example, the control unit 50 performs ray tracing calculation based on the position of the far point FP, the refractive index of each translucent body, and the anterior segment shape information.

The control unit 50 traces a ray (e.g., ray Lx in FIG. 9) incident from the far point FP toward the eye E to be examined, refracts the ray by each translucent body of the eye E to be examined, and aligns the ray with the optical axis. Find the position of the crossing point. Details of the ray tracing calculation will be described later. For example, the position of the fundus oculi Ef is obtained by such ray tracing calculation. The control unit 50 derives the distance between the corneal vertex C and the fundus Ef as the axial length AL.

<Display output (S6)>
Finally, the axial length AL is displayed on the monitor 16 . In this embodiment, the axial length AL is displayed together with at least one of the corneal shape information and the eye refractive power (SPH, CYL, AXIS) of the eye E to be examined. For example, if there is a past axial length measurement result for the subject's eye E, the current measurement result may be displayed together with the past measurement result.

<Ray tracing calculation>
A ray tracing calculation for deriving the axial length will be described. In this embodiment, for convenience of explanation, it is assumed that the refractive index of each translucent body of the subject's eye E is constant and there is no refraction change inside each. However, it is not necessarily limited to this, and even if the axial length is derived in consideration of the change in the refractive index inside the translucent body (for example, the change in the refractive index between the inside and outside of the crystalline lens) good.

By the way, in the expression format of eye refractive power by SPH, CYL, and AXIS, which are widely used, SPH indicates the refractive power related to the strong principal meridian (or weak principal meridian). is not necessarily an appropriate value in the ray tracing of For example, consider the case where SPH=-5D, CYL=-2D, and AXIS=30°. In this case, if a horizontal cross section is obtained in the example of the above optical system, the refractive power at this cross section is neither −5D nor −7D with CYL added.

On the other hand, in this embodiment, the on-plane eye refractive power, which is the eye refractive power on the cutting plane, is obtained, and the position of the far point FP is set based on the on-plane refractive power. Here, the refractive power P on an arbitrary surface is expressed by the following formula. However, θ is an angle with respect to the horizontal plane, and the horizontal direction is 0°.

　P(θ)=SPH+CYL×[sin2(θ-A)]

FIG. 10 is a diagram showing the refractive power in each meridional direction when the subject's eye E has SPH=-5D, CYL=-2D, and AXIS=30°. For example, the cutting plane in this embodiment is a horizontal plane (θ=0°). Therefore, if the subject's eye E has SPH=-5D, CYL=-2D, and AXIS=30°, P(0°)=-5.5D is calculated. In this case, the distance from the corneal vertex C to the far point FP on the cut plane is 12+1000/5.5=194 mm if VD=12 mm.

The control unit 50 traces the ray from the far point FP set in this way. For example, a ray (for example, ray Lx in FIG. 9) directed from the far point FP to a certain position (for example, a position of φ6 mm at the position of the pupil of the subject's eye (about 3 mm behind the cornea)) is guided. It should be noted that setting the fixed position to the position of the pupil of the subject's eye at φ6 mm is merely an example, and can be changed as appropriate.

This light ray is first refracted at the anterior surface of the cornea. The intersection point of the ray with the anterior corneal surface is calculated based on the radius of curvature Ra of the anterior corneal surface, the position of the far point FP, and the ray angle at the far point FP. Furthermore, the incident angle of the light ray at the intersection is calculated. A light ray that reaches the anterior surface of the cornea changes direction at a fixed angle of refraction with respect to the angle of incidence according to Snell's law. In this way, the rays at each transparent body interface are traced sequentially. At that time, the anterior segment shape information (Ra, Rp, CT, ACD, ra, rp, LT) acquired based on the corneal shape information and the cross-sectional image 70 (Scheimpflug image) is It is used as appropriate to give the intersection points. In the present embodiment, finally, after exiting the posterior surface of the lens, the intersection point (that is, the position of the fundus oculi Ef) that intersects with the axis of the eye (here, the visual axis) is obtained. The distance from the intersection to the corneal vertex C (the origin here) is used as the axial length AL.

When using the anterior segment shape information (Ra, Rp, CT, ACD, ra, rp, LT) in the ray tracing calculation, in this embodiment, at least the radius of curvature Ra of the anterior surface of the cornea is Values based on the corneal Purkinje image of the image index are used, and for the remaining values, values based on the cross-sectional image 70 (Scheimpflug image) are used. This is because the measurement accuracy of the corneal anterior surface shape based on the corneal Purkinje image is generally higher than that based on the Scheimpflug image. As described above, in this embodiment, at least each value of the corneal curvature, the astigmatism power, and the astigmatism axis angle is acquired as the corneal shape information. From these values, the corneal curvature at the cut plane (curvature of the anterior corneal surface) can be determined using a technique similar to that used to determine the refractive power for the cut plane. The reciprocal of the obtained value may be used as Ra.

The axial length AL of the subject's eye E can be obtained by tracing the light rays directed to such a fixed position. However, the method of ray tracing is not limited to the above method. For example, a point to be imaged from the far point FP may be obtained by paraxial calculation. In addition, a point to be imaged from the far point FP may be obtained in consideration of a plurality of rays incident on the subject's eye E at different positions. For example, ray tracing for paraxial rays and rays directed to fixed positions different from the paraxial rays may be combined. When multiple rays are ray-traced, the final measured value (calculated value) of the axial length may be the average of the axial lengths of each ray-traced (weighted average). can also be used).

Also, the axial length AL may be obtained by tracing the light rays directed to the measurement area (φ2 mm to φ4 mm on the pupil) by the measurement optical system 100 . For example, ray tracing may be performed for each of a plurality of rays directed to a region of φ2 mm to φ4 mm on the pupil, and the average value of the axial length obtained by each ray tracing may be obtained as a calculation result. Since ray tracing is performed under more appropriate conditions, the axial length can be obtained more accurately.

A predetermined offset value may be added to the axial length value obtained in this embodiment. The offset value corrects the error between the calculated value and the measured value.

Further, ray tracing may be performed by tracing a ray emitted from the far point FP and passing through the circumferential region on which the point image index for corneal topography measurement is projected. As a result, the conditions for ray tracing become more appropriate, and the axial length can be obtained more accurately.

FIG. 11 is an example of a flowchart showing the control operation of the ophthalmologic apparatus. In <capturing an anterior segment cross-sectional image (S4)>, the cross-sectional image of the anterior segment may not be appropriately acquired depending on the state of the anterior segment of the eye E to be examined. For example, the subject's eyelid and eyelashes are reflected, the pupil of the subject's eye E is miosis (the pupil diameter PDM is short), and the like. In the following, miosis of the eye E to be examined will be taken as an example.

FIG. 11 is an appropriate cross-sectional image 70 taken in a state where the subject's eye E is not miotic. FIG. 12 is an inappropriate cross-sectional image 70 captured with the subject's eye E miotic. For example, the pupil diameter PDM2 when the pupil of the subject's eye E is constricted is shorter than the pupil diameter PDM1 when the pupil is not constricted. In this state, the return light that has illuminated the anterior segment of the subject's eye is likely to be eclipsed by the iris, and there is a possibility that the imaging range in the depth direction (Z direction) of the anterior segment will be insufficient. In particular, the vignetting of such returned light has a large effect on deeper positions in the anterior segment of the eye. In some cases.

Also, for example, when the pupil diameter of the subject's eye E is small, the detection width in the horizontal direction (X direction) of the anteroposterior surface of the lens becomes narrow. In other words, the number of pixels in the longitudinal direction of the slit light is reduced on the front and rear surfaces of the lens. In this case, an error is likely to occur in calculating the radius of curvature of the front and rear surfaces of the lens. More specifically, fitting a circle with at least 3 pixel locations will use 3 narrow points, so a 1 pixel shift will show up as an error rather than using 3 wide points. Cheap.

Therefore, when proceeding to <Analysis of anterior segment cross-sectional image (S41)>, in the image processing of the cross-sectional image 70, if the subject's eye E has miosis, part of the parameter information must be correctly acquired. can't For example, if the parameter information cannot be acquired in the first place, the control unit 50 may return to step S4 and capture the cross-sectional image 70 again. Also, if the accuracy of the parameter information is considered to be low, the control unit 50 may proceed to step S42 and select an effective measurement value to be used for calculating the axial length.

In <Selection of anterior segment shape information (S42)>, the control unit 50 selects parameter information to be used for calculating the axial length from a plurality of pieces of parameter information included in the anterior segment shape information of the eye E to be examined. . More specifically, information representing the pupillary condition in the anterior segment of the subject's eye E is obtained, and effective measurement values are selected based on this information. In this embodiment, when the cross-sectional image 70 of the anterior segment is image-processed in step S41, information representing the pupil state is obtained together with the anterior segment shape information. For example, the pupil diameter (PDM) is acquired as the information representing the pupil state.

FIG. 15 is an example of measured values and effectiveness of multiple parameter information. The control unit 50 may select parameter information to be used for calculating the axial length by excluding specific parameter information from a plurality of pieces of parameter information according to the pupil diameter of the eye E to be examined. For example, if the pupil diameter is shorter, the deeper part of the anterior segment is poorly imaged, and whether or not the measured value of the parameter information is considered valid may be associated in advance for each pupil diameter. For example, if the pupil diameter is φ2 mm or less, the detection of the anterior and posterior surface of the lens is considered inappropriate, and the measured values of the curvature radius of the anterior and posterior surface of the lens and the thickness of the lens are considered invalid. A correspondence may be established such that thickness and anterior chamber depth measurements are considered valid. Of course, the correspondence between the pupil diameter and whether or not the measured value is valid may be different from that of the present embodiment. This selects valid measured values as appropriate parameter information for use in calculating the axial length of the eye.

Note that the control unit 50 may replace invalid measured values excluded from a plurality of parameter information with assumed values. For example, a standard value based on a model eye, an average value based on statistical data, etc., a past measurement value of the subject's eye E, etc. may be applied as hypothetical values. In addition, an estimated value that can be obtained in consideration of an effective measurement value selected as parameter information used for calculating the axial length and a general ratio of the corneal anterior surface and the lens anterior surface of the eye, etc. may be applied as hypothetical values.

Thus, when selecting an effective measurement value to be used for calculating the axial length of the eye, the control unit 50 performs ocular refractive power of the eye to be examined E and The axial length may be calculated based on valid measurement values among the plurality of parameter information in the anterior segment shape information. Note that the control unit 50 may calculate the axial length using an assumed value obtained by replacing the invalid measured value in addition to the eye refractive power and the valid measured value.

FIG. 15 is an example of a flowchart showing the control operation of the ophthalmologic apparatus. As described above, when proceeding to <Analysis of anterior segment cross-sectional image (S41)>, in the image processing of the cross-sectional image 70, if the subject's eye E has miosis, a plurality of Part of the parameter information cannot be obtained correctly. Therefore, the control unit 50 determines the quality of a plurality of pieces of parameter information in <parameter information quality determination (S43)>. For example, based on the luminance information of the cross-sectional image 70, the quality of each piece of parameter information may be determined.

FIG. 16 shows changes in luminance values corresponding to the appropriate cross-sectional image 70 shown in FIG. FIG. 17 shows changes in brightness values corresponding to the inappropriate cross-sectional image 70 shown in FIG. The control unit 50 detects the rise and fall of luminance in the depth direction of the subject's eye at the center of the cross-sectional image 70 (that is, on the optical axis L1). For example, as shown in FIGS. 12 and 16, when the pupil of the eye to be examined E is not miotic, the boundaries between the anterior and posterior surfaces of the cornea and the anterior and posterior surfaces of the lens are clearly visible, and the gradients of the rise and fall of the luminance value are steep. become. On the other hand, for example, as shown in FIGS. 13 and 17, when the pupil of the subject's eye E is miotic, the boundaries between the anterior and posterior surfaces of the cornea and the anterior surface of the lens are clearly captured, but the boundary of the posterior surface of the lens is not clearly captured. , and the fall of the luminance value on the posterior surface of the lens becomes gentle. As a result, the posterior surface of the lens is detected at a different position than it actually is.

The control unit 50 determines whether or not the anterior and posterior surfaces of the cornea and the anterior and posterior surface of the lens are satisfactorily imaged from the rise and fall of the luminance value of the tissue in the cross-sectional image 70 . For example, a reference angle based on experiments or simulations may be set in advance for the gradient of the luminance value of each tissue. If the gradient of the luminance value of a certain tissue is equal to or greater than a predetermined angle, it may be determined that the image was captured well, and if the angle is less than the predetermined angle, it may be determined that the image was not captured satisfactorily. Note that the rise and fall of the luminance value corresponding to each tissue may be expressed not only as an angle but also as an inclination. Moreover, it is also possible to use the width in the depth direction from the maximum value to the minimum value of the luminance value corresponding to each tissue as a criterion for such determination.

Furthermore, the control unit 50 determines the quality of the plurality of parameter information included in the anterior segment shape information based on the determination result of whether or not each tissue in the cross-sectional image 70 has been satisfactorily imaged. For example, for parameter information based on pixel positions of tissue that is not well imaged, the analysis result may be determined to be unsatisfactory. Further, for example, for parameter information based on the pixel positions of well-imaged tissue, the analysis result may be determined to be good. As an example, if the posterior lens surface is not well imaged, the posterior lens radius of curvature and lens thickness are not valid measurements, and the anterior and posterior corneal radius of curvature, corneal thickness, anterior chamber depth, and anterior lens radius of curvature are not valid measurements. may be a valid measurement.

It should be noted that in this embodiment, an evaluation value for evaluating the reliability of a plurality of parameter information in the anterior segment shape information may be obtained, and the quality of each parameter information may be determined based on this evaluation value. In this case, the control unit 50 may determine an evaluation value indicating whether or not imaging of each tissue is good according to the degree of the gradient of the luminance value of each tissue in the cross-sectional image 70 .

For example, the control unit 50 may express the difference between the reference angle provided for the gradient of the luminance value of each tissue and the actual gradient angle in five stages of numerical values. For example, the closer the angle of the actual gradient of the luminance value is to the reference angle, the higher the 5-level numerical value is set, and the farther from the reference angle, the lower the 5-level numerical value is set. That is, for example, the smaller the difference between the actual gradient angle and the reference angle, the higher the numerical value is set, and the larger the difference, the lower the numerical value is set. Note that the correspondence relationship between the allowable range of the angle difference and the numerical value may be stored in the storage unit. If the evaluation value of a certain tissue is below a predetermined numerical value, the control unit 50 determines that the tissue is not well imaged, and treats the analysis result (that is, the measured value) of the related parameter information as invalid. good too.

In <Axial Length Calculation (S5)>, the control unit 50 may calculate the axial length using both valid measurement values and invalid measurement values among a plurality of pieces of parameter information. Further, for example, the eye axial length may be calculated using both effective measured values and hypothetical values obtained by replacing ineffective measured values among a plurality of pieces of parameter information.

In this embodiment, both axial lengths are calculated using only measured values or measured values and hypothetical values as a plurality of parameter information in the anterior segment shape information. As the assumed value, an estimated value that can be obtained in consideration of the ratio of general corneal shape and lens shape is applied. For example, by multiplying the radius of curvature (measured value) of the anterior surface of the cornea by a predetermined ratio value, the radius of curvature (estimated value) of the posterior surface of the cornea can be obtained. Similarly, by multiplying the radius of curvature (measured value) of the anterior surface of the lens by a predetermined ratio value, the radius of curvature (estimated value) of the posterior surface of the lens can be obtained. The control unit 50 may multiply valid measurements of the parameter information by such ratio values to obtain estimated values to replace invalid measurements.

FIG. 18 is an example showing changes over time in the axial length of the eye. In <display output (S6)>, the control unit 50 displays the axial length using only the measured values as a plurality of parameter information and the axial length using the measured values and assumed values so as to be distinguishable. may For example, in the past and present axial lengths, the axial length using only the measured value (first axial length AL1) and the axial length using the measured value and assumed value (second axial length AL2 ) and may be displayed so as to be distinguished from each other. For example, here, a graph is displayed in which the axial length of each examination date (age) is arranged in chronological order. Of course, the display mode is not limited.

If there are multiple measurement results with different time series, it is also possible to predict the future axial length using these axial lengths. In this case, the past and present axial lengths may be displayed so as to be distinguishable from the predicted axial lengths. In addition, the change over time may be displayed for each parameter information included in the anterior segment shape information, not limited to the axial length of the eye. For example, temporal changes in corneal thickness, lens thickness, anterior chamber depth, and the like may be displayed.

As described above, for example, the ophthalmologic apparatus of the present embodiment uses infrared light as measurement light in the eye refractive power measurement optical system for acquiring the eye refractive power of the eye to be examined. In a cross-sectional imaging optical system for acquiring an anterior segment cross-sectional image, red visible light or infrared light is used as illumination light. As a result, glare of the subject due to the illumination light can be reduced, and the eye axial length can be obtained in a state in which the burden of capturing an anterior segment cross-sectional image is reduced. In particular, the use of red visible light or infrared light is more effective for young people, including children, because they are greatly affected by glare.

Further, for example, the ophthalmologic apparatus of the present embodiment emits measurement light (infrared light) for the eye refractive power measurement optical system and illumination light (red visible light or infrared light) for the cross-sectional imaging optical system at different wavelengths. Configure. This makes it possible to facilitate the configuration of each optical system for reducing the glare of the illumination light on the subject.

Also, for example, in the ophthalmologic apparatus of this embodiment, the wavelength of the illumination light in the cross-section imaging optical system is configured to be shorter than the wavelength of the measurement light in the eye refractive power measurement optical system. For example, the measurement light from the eye refractive power measurement optical system is focused on the fundus, and the illumination light from the cross-sectional imaging optical system is focused on the anterior segment of the eye. Easy to feel. For this reason, in the wavelength region from red visible light to infrared light, the measurement light that is easily perceived as glare is set on the long wavelength side where visibility is low, and the illumination light that is less likely to be perceived as glare is set to have high visibility. By setting the wavelength to the short wavelength side, the burden on the subject can be reduced.

Also, for example, the ophthalmologic apparatus of this embodiment uses near-infrared light with a peak wavelength between 650 nm and 800 nm as the illumination light in the cross-sectional imaging optical system. This makes it possible for the subject to feel less glare and to use photodetectors with various wavelength sensitivity ranges. For example, a Si image sensor sensitive to wavelengths from the ultraviolet region to the near-infrared region, an InGaAs image sensor sensitive to wavelengths in the near-infrared region, or the like can be used.

Also, for example, in the ophthalmologic apparatus of this embodiment, the cross-section imaging optical system is configured with a photodetector having a semiconductor substrate made of silicon. For example, a Si image sensor is less sensitive to near-infrared wavelengths (particularly longer wavelengths than 800 nm) than an InGaAs image sensor, but is capable of sufficiently obtaining a cross-sectional image of the anterior segment of the eye. Furthermore, since the Si image sensor is cheaper than the InGaAs image sensor, the cost of the device can be reduced.

<transformation example>
In this embodiment, the measurement light source 111 in the projection optical system 100a of the measurement optical system 100 emits near-infrared light as the measurement light. However, the configuration is not limited to this. For example, an optical member for limiting the wavelength of the measurement light may be arranged in the optical path of the measurement light from the measurement light source 111 . Similarly, in this embodiment, in the illumination optical system 300a of the cross-sectional imaging optical system, the light source 311 emits red visible light or near-infrared light as illumination light. . For example, an optical member for limiting the wavelength of the illumination light may be arranged in the optical path of the illumination light from the light source 311 . For example, such an optical member that limits the wavelengths of measurement light and illumination light may be a cut filter.

In the present embodiment, the illumination optical system 300a of the cross-sectional imaging optical system has been described as an example of a configuration in which red visible light or near-infrared illumination light is projected, but the present invention is not limited to this. For example, it may be configured to use visible light different from red as illumination light. When the eye to be examined E is irradiated with visible light (in particular, light with high luminosity), the pupil of the eye contracts. Further, for example, in addition to illumination light having a wavelength of red visible light or near-infrared light, illumination light having a different wavelength may be selectively projected. As an example, the configuration may be such that at least one of visible light such as blue visible light, green visible light, and white visible light can be projected.

In this case, the control unit 50 controls a plurality of light sources and switches between lighting and extinguishing of each light source to generate illumination light having a wavelength of red visible light (or near-infrared light) and red visible light (or near-infrared light). Illumination light having a wavelength different from that of external light) may be projected toward the subject's eye. Alternatively, the control unit 50 controls and switches an optical member arranged in the optical path of the illumination light from the light source, so that illumination light having a wavelength of red visible light (or near-infrared light) and red visible light ( or near-infrared light) may be projected toward the subject's eye. Accordingly, it is possible to selectively use illumination light considering the glare of the subject's eye and illumination light considering the condition of the subject's eye (cataract, etc.) according to the situation. For example, even if the subject's eye has cataracts or the like, the cross-sectional image 70 can be properly acquired and the axial length of the eye can be measured.

In this embodiment, the configuration for acquiring one cross-sectional image 70 using the cross-sectional imaging optical system has been described as an example, but the configuration is not limited to this. For example, it may be configured to acquire a plurality of cross-sectional images using a cross-sectional imaging optical system. In the cross-sectional imaging optical system, the irradiation optical system 300a emits red visible light or near-infrared illumination light to reduce the glare of the subject's eye. It is possible to obtain

In this case, the control unit 50 may cause the light source 311 to emit illumination light all the time, and the imaging element 321 to always capture the return light of the illumination light, thereby obtaining a cross-sectional image of the subject's eye as a moving image. Further, in this case, the control unit 50 may cause the light source 311 to emit illumination light every time a predetermined time elapses (for example, every second) to obtain a cross-sectional image of the subject's eye as a still image. good. Note that the imaging device 321 may capture the returning light each time a predetermined time elapses in conjunction with the projection timing of the illumination light, or may capture the returning light all the time. In this case, the control unit 50 may cause the imaging element 321 to capture the return light of the illumination light every time a predetermined time elapses, and obtain a cross-sectional image of the subject's eye as a still image. Note that the light source 311 may emit illumination light each time a predetermined time elapses in conjunction with the imaging timing of the imaging element 321, or may emit illumination light all the time. For example, by continuously acquiring cross-sectional images of the subject's eye, it is possible to grasp the pupillary state (miosis and mydriasis) of the subject's eye and the accommodation state of the subject's eye. By selecting an appropriate cross-sectional image from a plurality of cross-sectional images, the axial length can be measured with high accuracy.

Arithmetic processing may be performed when cross-sectional images of the subject's eye are continuously acquired. For example, the axial length can be accurately measured by synthesizing cross-sectional images of the subject's eye by averaging processing. Of course, a representative value (for example, average value, median value, mode value, etc.) may be calculated for the anterior segment shape information that can be obtained based on the cross-sectional image of the subject's eye. A representative value may be calculated for the axial length obtained by the ray tracing calculation using the eye refractive power of the subject's eye and the anterior segment shape information. As for the anterior segment shape information and the eye axial length, the remaining numerical values excluding the maximum and minimum values may be used to calculate the representative value. These also allow the axial length to be measured with high accuracy. Furthermore, in such arithmetic processing, outliers may be excluded based on variations in each data.

Note that the cross-section imaging optical system may include a rotation mechanism for rotating the slit 312 of the irradiation optical system 300a and a moving mechanism for moving the imaging device 321 of the light receiving optical system 300b. For example, when cross-sectional images of the subject's eye are continuously acquired, the Scheimpflug relationship between the slit 312 and the imaging element 321 may be maintained, and the positions thereof may be changed by controlling the rotating mechanism and the moving mechanism. good. For example, this may obtain a plurality of cross-sectional images each having a different angle of the light-section plane with respect to the anterior segment. Also, a plurality of such cross-sectional images may be synthesized to obtain a three-dimensional cross-sectional image.

In the present embodiment, a configuration for acquiring a cross-sectional image 70 of the eye to be inspected using the cross-sectional imaging optical system after measuring the eye refractive power of the eye to be inspected using the measurement optical system 100 has been described as an example. is not limited to For example, the configuration may be such that the eye refractive power of the eye to be inspected and the cross-sectional image 70 of the eye to be inspected are acquired at the same timing (in parallel). This makes it possible to improve the accuracy of the axial length.

In this case, the control unit 50 controls both the measurement light from the measurement light source 111 in the projection optical system 100a and the illumination light from the light source 311 in the irradiation optical system 300a, and directs both lights toward the subject's eye. light up. Note that the light projection does not necessarily have to start at the same time. Further, the control unit 50 controls both the image sensor 125 in the light receiving optical system 100b and the image sensor 321 in the light receiving optical system 300b to capture (capture) the ring image and the cross-sectional image 70 at the same timing.

For example, in the measurement of the ocular refractive power of the subject's eye, the adjustment is canceled due to fog, but there is a possibility that the adjustment may be made again when acquiring a cross-sectional image of the anterior segment. may differ. In addition, for example, in the measurement of the eye refractive power of the subject's eye, the use of near-infrared light results in a pupillary state in which there is no miosis. When acquiring a cross-sectional image of the anterior segment, red visible light or near-infrared light with a wavelength that does not give glare to the subject's eye is used, resulting in a pupillary state without miosis. There is However, if the measurement of the eye refractive power and the acquisition of the cross-sectional image are performed at the same timing, the eye axial length can be calculated with the pupil state and accommodation state of the eye to be examined matched, and the accuracy is improved. By suppressing the miosis of the subject's eye, it becomes easier to obtain a good cross-sectional image in which the anterior segment of the eye is captured even deeper.

In this embodiment, the alignment of the subject's eye and the ophthalmologic apparatus 10 is described as an example of a configuration in which the alignment is executed as the first step S1 in the flowcharts shown in FIGS. . For example, alignment between the subject's eye and the ophthalmologic apparatus 10 may be performed as appropriate during the progress of the flowchart. For example, it may be performed before measuring the eye refractive power of the subject's eye (between steps S2 and S3) or before acquiring a cross-sectional image of the anterior segment (between steps S3 and S4).

As an example, take the case of performing alignment again before obtaining a cross-sectional image of the anterior segment. For example, the control unit 50 may detect the corneal vertex position from cross-sectional images sequentially generated by the imaging device 321 . Further, for example, the control unit 50 may move the measurement unit 11 with respect to the subject's eye E so as to align the corneal vertex position with a predetermined position set in advance within the cross-sectional image. For example, depending on the corneal curvature of the eye to be inspected E, the working distance between the eye to be inspected E and the ophthalmologic apparatus 10 may deviate slightly. A cross-sectional image (capture image) can be acquired while maintaining an appropriate working distance. As a result, the focus of the cross-sectional image is stabilized, and the axial length can be calculated with high accuracy.

In this embodiment, the actual axial length of the eye to be inspected may differ from the axial length derived by ray tracing calculation based on the eye refractive power of the eye to be inspected and the shape information of the anterior segment of the eye. That is, there may be a deviation between the actual axial length and the calculated axial length. It is considered that this can occur, for example, by making the refractive index of each translucent body of the subject's eye constant. This is because the refractive index adopted from the model eye or literature values does not necessarily match the individual eye.

Therefore, the examiner may arbitrarily select a model eye or a literature value to change the refractive index. The refractive index may be changed by directly inputting a numerical value by the examiner. Further, the axial length obtained by the ray tracing calculation may be multiplied by a coefficient set in advance based on experiments or simulations. Note that the number of such coefficients is not limited to one, and a plurality of coefficients corresponding to at least one of country, region, age, and the like may be prepared. As a result, the axial length can be accurately derived with a value closer to the actual axial length.

Further, for example, a configuration may be adopted in which, separately from the cross-sectional image 70 of the anterior segment, refractive index information regarding the refractive index of the translucent body is obtained, and the refractive index information is used to derive the axial length AL. In other words, in obtaining the axial length AL, the refractive index of the translucent body based on the refractive index information may be further considered. As an example, the refractive index information may include the refractive index of the lens. It is known that the refractive index of the lens changes with aging. Therefore, the storage unit of the ophthalmologic apparatus 10 may have a calculation formula or a lookup table in which the refractive index of the lens is associated with each age. In this case, by inputting the age of the subject, it is possible to acquire the refractive index according to the age. The control unit 50 may perform ray tracing calculation using such a refractive index of the crystalline lens. This also allows the axial length to be derived with high accuracy, with a value closer to the actual axial length.

In this embodiment, as one of the anterior segment state information representing the state of the anterior segment, the configuration for acquiring the information representing the pupillary state (pupil diameter PDM) has been described as an example, but the present invention is not limited to this. For example, as the anterior segment state information, information representing the accommodation state may be acquired. For example, the information representing the accommodation state may be lens thickness.

For example, the lens thickness LT1 of the subject's eye E in a state in which accommodation is canceled is thicker than the lens thickness LT1 in a state in which accommodation has been performed. As a result, the anterior chamber depth ACD becomes shorter and the radius of curvature of the anterior lens surface becomes smaller. The radius of curvature of the anterior and posterior surface of the cornea, the corneal thickness, and the radius of curvature of the posterior surface of the lens hardly change. The axial length of the subject's eye E is calculated using the eye refractive power and effective measurement values among the plurality of parameter information in the anterior segment shape information, but the accommodation conditions are different at the time of each acquisition. This affects the accuracy and reproducibility of measured values, making it difficult to accurately measure the axial length.

For this reason, the control unit 50 may select valid measured values of a plurality of parameter information according to the accommodation state of the eye E to be examined. The lens thickness obtained by image processing of the cross-sectional image 70 may be used together with the lens thickness as information representing the accommodation state. For example, considering that the eye refractive power is acquired in a state in which accommodation of the eye to be examined is canceled, if the lens thickness is equal to or greater than a predetermined thickness, the depth of the anterior chamber, the radius of curvature of the front surface of the lens, and the lens thickness are measured. Values may be discarded as not valid and measurements of the anterior and posterior corneal radius of curvature, the corneal thickness, and the posterior lens radius of curvature may be considered valid and selected.

Further, for example, even if the eye refractive power is acquired while the subject's eye is being accommodated, if the lens thickness is the same when the eye refractive power is acquired and when the cross-sectional image 70 is captured, the axial length can be accurately determined. It is possible to calculate In this case, the control unit 50 may consider at least the measured values of the radius of curvature of the front surface of the lens and the thickness of the lens to be valid and select them. When the subject's eye is adjusted, miosis occurs at the same time, and detection of the posterior surface of the lens becomes particularly inappropriate. Therefore, when the cross-sectional image 70 is captured with the subject's eye adjusted, the controller 50 may consider the measured value of the radius of curvature of the posterior surface of the lens to be invalid and exclude it.

In this embodiment, the configuration for acquiring the pupil diameter PDM using the cross-sectional image 70 of the anterior segment has been described as an example, but the configuration is not limited to this. For example, the pupil diameter PDM may be obtained using an observation image captured by the front imaging optical system 200 . The control unit 50 may obtain the pupil diameter by performing image processing on the observed image and detecting the pupil using luminance information.

At this time, the control unit 50 controls the front imaging optical system 200 and the cross-sectional imaging optical system (the irradiation optical system 300a and the light receiving optical system 300b), and simultaneously captures the observation image and the cross-sectional image 70. It may be executed (at the same timing). In this case, the control unit 50 controls both the imaging element 205 in the front optical system 200 and the imaging element 321 in the light receiving optical system 300b to capture the observed image and the cross-sectional image 70 at the same timing. Since the pupil of the subject's eye E changes over time due to fluctuations in breathing and the like, it is preferable to match the acquisition timing of the pupil diameter with the acquisition timing of the cross-sectional image 70 . As a result, effective measurement values in the anterior segment shape information are appropriately selected, and as a result, the axial length can be calculated with high accuracy. Of course, there may be a time difference that does not cause a significant difference in the pupil state of the subject's eye.

In the present embodiment, the time between the measurement of the eye refractive power of the subject's eye and the photographing of the cross-sectional image 70 is made as short as possible, thereby suppressing misalignment and changes in the pupillary state and accommodation state. was described as an example, but it is not limited to this. For example, there may be a certain amount of time between the measurement of eye refractive power and the imaging of cross-sectional images. In this case, since miosis and accommodation are more likely to occur, at least one of the observed image and the cross-sectional image 70 may be continuously acquired, and at least one of the pupil diameter and the lens thickness may be monitored.

The control unit 50 may capture the observation image and the cross-sectional image 70 when measuring the refractive power of the eye, acquire the pupil diameter and the lens thickness, and store them in the storage unit. Furthermore, the control unit 50 captures the observation image and the cross-sectional image 70 when the cross-sectional image 70 is acquired, and captures the cross-sectional image 70 at the timing when the pupil diameter and the lens thickness become equal to the stored values. good too. Of course, the pupil diameter and the lens thickness may be provided with an allowable range for determining whether or not they are equal. The state of the anterior segment of the subject's eye (pupil state and accommodative state) constantly changes, and these influences cannot be avoided in the acquisition of the eye refractive power and the anterior segment cross-sectional image. However, if each result is obtained under equal conditions, the accuracy and reproducibility of the axial length are likely to be maintained. It should be noted that even if the pupil diameter and lens thickness are different between when the eye refractive power is measured and when the cross-sectional image 70 is captured, it is possible to roughly calculate the axial length of the eye.

In the present embodiment, the state of the anterior segment is assumed to be appropriate when measuring the eye refractive power of the eye to be inspected, and the configuration of acquiring the state of the anterior segment when the cross-sectional image 70 of the eye to be inspected is captured is taken as an example. However, it is not limited to this. For example, the configuration may be such that the state of the anterior segment of the eye is acquired also in the measurement of the eye refractive power. That is, the configuration may be such that the state of the anterior segment at the timing of acquiring the eye refractive power and the state of the anterior segment at the timing of acquiring the cross-sectional image of the anterior segment are acquired. For example, since there may be a discrepancy in the state of the anterior segment between the measurement of eye refractive power and the taking of cross-sectional images of the anterior segment, it is possible to easily compare the two by acquiring the pupillary and accommodation conditions at each timing. and the axial length can be obtained more accurately.

In this embodiment, the configuration for acquiring the cross-sectional image 70 of the eye to be inspected after measuring the eye refractive power of the eye to be inspected has been described as an example, but the configuration is not limited to this. For example, the configuration may be such that the eye refractive power of the eye to be inspected and the cross-sectional image 70 of the eye to be inspected are acquired in parallel (at the same timing). In this case, the control unit 50 controls both the measurement light from the measurement light source 111 in the projection optical system 100a and the illumination light from the light source 311 in the irradiation optical system 300a, and directs both lights toward the subject's eye. light up. Note that the light projection does not necessarily have to start at the same time. Further, the control unit 50 controls both the image sensor 125 in the light receiving optical system 100b and the image sensor 321 in the light receiving optical system 300b to capture the ring image and the cross-sectional image 70 at the same timing. For example, this obtains an eye refractive power and a cross-sectional image 70 with fog added to the subject's eye.

The condition of the subject's eye may differ at each acquisition timing, and it is difficult to avoid the effects of miosis and accommodation on the refractive power of the eye and the anterior segment shape information based on the cross-sectional image 70 . For example, in the measurement of the ocular refractive power of the eye to be examined, miosis is suppressed and accommodation is canceled. There is also the possibility of However, if the eye refractive power measurement (acquisition of a ring image) and cross-sectional image acquisition are performed simultaneously, the pupillary state and accommodation state of the subject's eye can be easily matched, and the axial length can be accurately calculated. can.

For example, by measuring the refractive power of the eye and obtaining a cross-sectional image at the same time, fog is added to the eye to be examined, and the anterior segment is in an appropriate state (i.e., the eye is unadjusted and the lens thickness is thin). ) to acquire cross-sectional images. Therefore, the control unit 50 can obtain measured values of parameters suitable for calculating the axial length of the eye, and accurately obtain the axial length of the eye. Furthermore, if the measured values of the parameters are not valid, the axial length can be obtained with high accuracy by replacing them with the assumed values.

In this embodiment, the configuration in which the rise and fall of the luminance value of each tissue is used to determine the quality of the anterior segment shape information based on the cross-sectional image 70 has been described as an example, but the present invention is not limited to this. For example, the pupil state of the subject's eye may be used to determine whether the anterior segment shape information is good or bad. In this case, the control unit 50 may acquire the pupil diameter as the pupil state by detecting the pixel position corresponding to the iris based on the luminance information of the cross-sectional image 70 . Also, based on this pupil diameter, it may be determined whether or not the anterior and posterior surfaces of the cornea and the anterior and posterior surfaces of the lens are satisfactorily imaged. Note that the control unit 50 can also acquire pupil state information (pupil diameter) using an observation image captured by the front imaging optical system 200 .

For example, when the pupil diameter of the subject's eye E is small, the detection width in the horizontal direction (X direction) of the anteroposterior surface of the lens becomes narrow. In other words, the number of pixels in the longitudinal direction of the slit light is reduced on the front and rear surfaces of the lens. Moreover, when the pupil diameter of the eye E to be examined is small, the boundary of the posterior surface of the lens may not be clearly captured. For this reason, the control unit 50 may change the tissue considered to be well imaged according to the pupil diameter of the eye E to be examined. For example, if the pupil diameter is φ2 mm or less, it may be considered that the anterior and posterior surfaces of the cornea are well imaged, and that the anterior and posterior surfaces of the lens are not well imaged. Further, the control unit 50 may determine the quality of a plurality of pieces of parameter information included in the anterior segment shape information, based on the determination result of whether or not each tissue was imaged satisfactorily. As an example, the anterior-posterior corneal radius of curvature, corneal thickness, and anterior chamber depth may be valid measurements, while the anterior-posterior lens radius of curvature and lens thickness may be invalid measurements.

It should be noted that if the detection width of each tissue in the horizontal direction is narrow, an error is likely to occur in calculating the radius of curvature. For example, in fitting a circle using at least three pixel positions, a deviation of one pixel is more likely to appear as an error in the radius of curvature when three points in a narrow area are used than when three points in a wide area are used. The effectiveness of the parameter information can be accurately determined by associating the pupil diameter with the imaging quality of each tissue in consideration of the change in the detection width accompanying the change in the pupil diameter.

In the present embodiment, the configuration in which one cross-sectional image is captured in capturing the cross-sectional image 70 using the cross-sectional image capturing optical system has been described as an example, but the present invention is not limited to this. For example, in capturing the cross-sectional image 70, a configuration in which a plurality of cross-sectional images are captured may be used. In this case, the control unit 50 may cause the imaging device 321 to capture the return light of the illumination light every time a predetermined time elapses (for example, every second). The illumination light from the light source 311 may be projected at predetermined time intervals in conjunction with the imaging timing of the imaging element 321, or may be projected at all times. For example, by continuously acquiring multiple cross-sectional images of the subject's eye, it becomes easier to include appropriate cross-sectional images, such as images in which eyelids and eyelashes are not reflected, images in which the subject's eye is not miotic, and the like. . The control unit 50 may use brightness information and evaluation information in a plurality of cross-sectional images to determine the quality of the parameter information corresponding to each.

By acquiring a plurality of anterior segment cross-sectional images, the control unit 50 acquires at least one of the first axial length AL1 and the second axial length AL2 based on the quality of a plurality of parameters corresponding to each. be able to. For example, it is possible to average the good values of the parameter for each tissue and, based on this, obtain the respective axial length. Note that such an average may be an average excluding outliers, which will be described later. Also, for example, the best parameter values for each tissue can be used to obtain the respective axial lengths. As a result, the axial length can be obtained with high accuracy.

When a plurality of cross-sectional images are continuously acquired using the cross-sectional image capturing optical system, outliers in the cross-sectional images or outliers in the anterior ocular segment shape information based on the cross-sectional images should be excluded in advance. may For example, the control unit 50 may identify and exclude these outliers through statistical processing. As an example, the luminance information and evaluation information obtained from a plurality of cross-sectional images may be excluded if they greatly deviate from the allowable range. By acquiring a plurality of anterior segment cross-sectional images and further removing outliers, the accuracy of the axial length can be further improved.

In this embodiment, the configuration in which the cross-sectional image 70 is captured using the cross-sectional image capturing optical system once in the flow charts shown in FIGS. 7, 11, and 15 has been described as an example. not. For example, the cross-sectional image 70 may be captured again based on the quality of the parameter information. In other words, the cross-sectional image 70 may be captured twice.

For example, the control unit 50 image-processes the cross-sectional image 70 acquired using the cross-sectional imaging optical system, and adjusts the light amount of the illumination light from the irradiation optical system 300a based on the luminance information detected thereby. good too. For example, if the predetermined tissue boundary cannot be detected, or if the predetermined tissue boundary is not clear, the amount of light from the light source 311 may be increased, or an optical member such as a filter may be inserted or removed in the optical path. You may Further, for example, the control unit 50 may capture the cross-sectional image 70 again after adjusting the amount of illumination light from the irradiation optical system 300a. As a result, the second cross-sectional image can be acquired in which the imaging condition of each tissue is improved with respect to the first cross-sectional image. In other words, even if the measured values are not obtained or the measured values are not accurate because at least some of the parameters are not well obtained, the possibility of obtaining appropriate values increases. As a result, each of the pieces of parameter information included in the anterior segment shape information can be obtained satisfactorily, and the axial length can be accurately obtained.

It should be noted that it is preferable to irradiate infrared light from the light source 311 in such adjustment of the amount of light in the irradiation optical system 300a. For example, in the case of infrared light, even if the amount of light increases, the examinee is less likely to feel glare, and miosis of the examinee's eye can be suppressed.

This embodiment exemplifies a configuration in which some of a plurality of parameters included in the anterior segment shape information are automatically changed from measured values to assumed values based on the analysis result of cross-sectional image information in the cross-sectional image 70. However, it is not limited to this. For example, the examiner may operate the operation unit (monitor 16) to manually change whether to use measured values or assumed values for some of the plurality of parameters. In this case, the control unit 50 may cause the monitor 16 to display guide information for assisting the examiner's determination based on the quality of the parameter information in the anterior segment shape information.

In this embodiment, a configuration in which some of the parameters included in the anterior segment shape information are replaced with an estimated value, which is one of hypothetical values, has been described as an example, but the present invention is not limited to this. For example, the examiner may operate the operating unit to select a value to be used as the hypothetical value. As an example, it may be possible to select at least one of a standard value based on a model eye, an average value based on statistical data, etc., a past measurement value of an eye to be examined, an estimated value, and the like.

Note that the ophthalmologic apparatus of the present embodiment projects measurement light toward the anterior segment of the eye to be examined, and detects return light of the measurement light from an oblique direction with respect to the projection optical axis of the measurement light. , a cross-sectional image capturing optical system for acquiring a cross-sectional image of the anterior segment of the eye to be inspected, and state information relating to the state of the anterior segment of the eye to be inspected, the state information including at least one of a pupillary state and an accommodation state. shape information acquisition means for acquiring shape information relating to the shape of the anterior segment, the shape information including a plurality of parameters, by analyzing the cross-sectional image of the anterior segment; and cross-sectional image capturing. An ophthalmologic apparatus comprising: an axial length acquiring means for controlling acquisition of an anterior segment cross-sectional image using an optical system, and acquiring the axial length of the eye to be inspected from the eye refractive power of the eye to be inspected and a plurality of parameters. The axial length obtaining means may select a selection parameter to be used for deriving the axial length from among the plurality of parameters based on the state information, and obtain the axial length from the selected parameter.

Further, in the ophthalmologic apparatus of the present embodiment, the axial length obtaining means changes non-selected parameters, which are different from the selected parameters, from the measured values to the assumed values among the plurality of parameters, and calculates the axial length from the selected parameters and the non-selected parameters. You can get the length.

Further, in the ophthalmologic apparatus of the present embodiment, the non-selected parameter may be a parameter of a translucent body located deeper than the iris of the subject's eye and including the crystalline lens.

Further, the ophthalmologic apparatus of the present embodiment includes an eye refractive power measuring optical system for acquiring the eye refractive power of the subject's eye, and the eye axial length acquiring means measures eye refractive power using the eye refractive power measuring optical system. Acquisition may be controlled.

Further, the ophthalmologic apparatus of this embodiment includes a front image capturing optical system for illuminating the anterior segment of the eye to be inspected and acquiring a front image of the anterior segment of the eye to be inspected. The state information may be acquired based on at least one of the cross-sectional image and the anterior segment front image.

Further, in the ophthalmologic apparatus of the present embodiment, the state information acquisition means is the first state of the anterior segment, and the first state information about the first state at the acquisition timing of the eye refractive power; The second state information about the second state at the acquisition timing of the anterior segment cross-sectional image may be acquired as the state information.

Further, in the ophthalmologic apparatus of the present embodiment, the eye axial length acquisition means acquires the eye refractive power using the eye refractive power measurement optical system and acquires the anterior segment cross-sectional image using the cross-sectional image capturing optical system. , may be performed in a state in which the first state and the second state of the anterior segment coincide.

Further, in the ophthalmologic apparatus of the present embodiment, the eye axial length acquisition means acquires an eye refractive power using an eye refractive power measurement optical system, acquires an anterior segment cross-sectional image using a cross-sectional image capturing optical system, can be run in parallel.

Further, the ophthalmologic apparatus of the present embodiment includes an eye refractive power measurement optical system for obtaining the eye refractive power of the eye to be examined, and a measuring light beam directed toward the anterior ocular segment of the eye to be examined. A cross-sectional image capturing optical system for acquiring a cross-sectional image of the anterior segment of the eye to be examined by detecting the return light of the measurement light from an oblique direction with respect to the optical axis. Shape information relating to the shape of the eye, which includes a plurality of parameters, is controlled to obtain shape information acquisition means for acquiring shape information, an eye refractive power measurement optical system, and a cross-sectional image capturing optical system, and eye refractive power and an axial length obtaining means for obtaining the axial length of the subject eye based on the plurality of parameters, wherein the axial length obtaining means obtains the first eye derived using the measured values of the plurality of parameters; An axial length and a second axial length derived using hypothetical values substituted for measured values of some of the parameters may be obtained.

Further, the ophthalmologic apparatus of the present embodiment includes determination means for determining whether at least one of a plurality of parameters is acceptable, and at least one of the first axial length and the second axial length based on the determination result of the determination means. selection means for selecting the derivation.

In addition, in the ophthalmologic apparatus of the present embodiment, the determining means may determine the acceptability of a plurality of parameters based on the brightness information of the anterior segment cross-sectional image.

Further, in the ophthalmologic apparatus of the present embodiment, the determination means may determine the quality of the plurality of parameters based on the evaluation information for evaluating the reliability of the plurality of parameters.

Further, in the ophthalmologic apparatus of the present embodiment, the axial length acquisition means acquires a plurality of anterior segment cross-sectional images, and the determination means determines whether the corresponding parameters are good or bad for each anterior segment cross-sectional image. The selection means may select derivation of the first axial length and the second axial length based on the quality of the plurality of parameters corresponding to the plurality of anterior segment cross-sectional images.

In addition, in the ophthalmologic apparatus of the present embodiment, the determining means excludes images having outliers from the plurality of anterior segment cross-sectional images, and determines the quality of the corresponding plurality of parameters for each of the remaining anterior segment cross-sectional images. You may

Further, in the ophthalmologic apparatus of the present embodiment, the axial length acquisition means adjusts the amount of measurement light in the cross-sectional imaging optical system based on the determination result of the determination means, and the shape information acquisition means acquires the axial length of the eye. The cross-sectional image of the anterior segment acquired after the light amount is adjusted by the means may be analyzed to acquire a plurality of parameters after adjustment, and the determination means may determine whether the parameters after adjustment are good or bad.

Further, in the ophthalmologic apparatus of the present embodiment, the eye axial length acquisition means is configured to operate the eye refractive power measurement optical system and the cross-sectional image capturing so that the eye refractive power and the cross-sectional image are acquired in a state where the subject's eye is covered with fog. The optical system may be controlled, and the first axial length and the second axial length may be obtained based on the anterior segment cross-sectional image obtained with fog added.

Further, the ophthalmologic apparatus of the present embodiment includes output means for outputting intraocular dimension information including the axial length of the eye, the output means comprising first dimension information obtained based on measured values of a plurality of parameters; and the second dimension information acquired based on hypothetical values obtained by replacing some of the measured values of the plurality of parameters, and the second dimension information may be output in a distinguishable manner.

In addition, in the ophthalmologic apparatus of the present embodiment, the output means may output temporal changes in dimension information.

10 ophthalmologic apparatus 50 control unit 100 measurement optical system 150 fixation target presentation optical system 200 front imaging optical system 300a irradiation optical system 300b light receiving optical system 400 index projection optical system

Claims (11)

Eye refractive power for projecting a first measurement light onto the fundus of an eye to be inspected and acquiring the eye refractive power of the eye to be inspected based on reflected light in which the first measurement light is reflected by the fundus. a measurement optical system;
A second measurement light is projected onto the anterior segment of the eye to be inspected, and a return light of the second measurement light is emitted from an oblique direction with respect to the projection optical axis of the second measurement light by a photodetector. a cross-sectional image capturing optical system for acquiring a cross-sectional image of the anterior segment of the subject eye by detecting;
an axial length acquiring means for acquiring the axial length of the subject eye based on the eye refractive power and the anterior segment cross-sectional image;
An ophthalmic device comprising:
The ophthalmologic apparatus, wherein the first measurement light is infrared light, and the second measurement light is red visible light or infrared light. The ophthalmic device of claim 1, wherein
The ophthalmologic apparatus, wherein the first wavelength of the first measurement light and the second wavelength of the second measurement light are different wavelengths. The ophthalmic device of claim 1 or 2,
The ophthalmologic apparatus, wherein the second wavelength of the second measurement light is shorter than the first wavelength of the first measurement light. In the ophthalmic device according to any one of claims 1 to 3,
The ophthalmologic apparatus, wherein the infrared light of the second measurement light is near-infrared light, and the second wavelength has a peak wavelength between 650 nm and 800 nm. In the ophthalmic device according to any one of claims 1 to 4,
An ophthalmologic apparatus, wherein the photodetector comprises a semiconductor substrate made of silicon. In the ophthalmic device according to any one of claims 1 to 5,
The cross-sectional imaging optical system is capable of selectively projecting light having a wavelength different from the second wavelength as the second measurement light,
The ophthalmologic apparatus, wherein the axial length obtaining means controls switching between projection of light having the second wavelength and projection of light having a wavelength different from the second wavelength. In the ophthalmic device according to any one of claims 1 to 6,
the axial length acquisition means controls projection of the second measurement light and detection of the return light by the photodetector;
An ophthalmologic apparatus characterized by obtaining a plurality of cross-sectional images of the anterior segment of the eye by continuously projecting the second measurement light and continuously detecting the return light by the photodetector. . The ophthalmic device of claim 7, wherein
The ophthalmologic apparatus, wherein the axial length acquisition means acquires the axial length by executing arithmetic processing based on the plurality of anterior segment cross-sectional images. In the ophthalmic device according to any one of claims 1 to 8,
The eye axial length acquisition means concurrently acquires the eye refractive power using the eye refractive power measurement optical system and acquires the anterior segment cross-sectional image using the cross-sectional image capturing optical system. An ophthalmic device characterized by: In the ophthalmic device according to any one of claims 1 to 9,
state information acquisition means for acquiring state information relating to the state of the anterior segment of the eye to be inspected, the state information including at least one of a pupillary state and an accommodation state;
shape information acquisition means for acquiring shape information about the shape of the anterior segment, the shape information including a plurality of parameters, by analyzing the anterior segment cross-sectional image;
with
The axial length acquiring means controls acquisition of the anterior segment cross-sectional image using the cross-sectional image capturing optical system, and determines the axial length among the plurality of parameters based on the state information. An ophthalmologic apparatus, wherein a selection parameter to be used is selected, and the axial length is obtained from the selection parameter. In the ophthalmic device according to any one of claims 1 to 10,
The axial length obtaining means is derived using a first axial length derived using the measured values of the plurality of parameters and an assumed value obtained by replacing the measured values of some of the plurality of parameters. and a second eye axial length.

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