WO2013001422A1

WO2013001422A1 - Method and device to obtain an ophthalmic image

Info

Publication number: WO2013001422A1
Application number: PCT/IB2012/053130
Authority: WO
Inventors: Shyam Vasudeva RAO; Chandrasekhar KUPPUSWAMY; Bharath HEGDE
Original assignee: Forus Health Pvt Ltd
Current assignee: Forus Health Pvt Ltd
Priority date: 2011-06-28
Filing date: 2012-06-21
Publication date: 2013-01-03
Anticipated expiration: 2013-12-28

Abstract

The present disclosure relates to ophthalmic imaging equipment for obtaining image of an eye. In an embodiment, the present disclosure provides for ophthalmic imaging device with a single light source, i.e., a multicolored LED and a single optical path for the light source. In particular, the ophthalmic device comprises a lens and an optical detector mounted at ends of the first optical path. The multicolored LED light source is provided at the opening of a second optical path. Other end of the second optical path intersects the first optical path with a half mirror at the intersection.

Description

METHOD AND DEVICE TO OBTAIN AN OPHTHALMIC IMAGE

TECHNICAL FIELD The present disclosure relates to ophthalmic imaging devices for obtaining image of retina of an eye. In particular, the disclosure relates to construction of the device using a single light source.

BACKGROUND

Ophthalmic imaging systems operate by directing light into a patient's eye to illuminate a portion of the retina. A camera then captures an image of the illuminated potion of the retina via light reflected from the retina. Such system is provided with for example two or more types of monochromatic light sources such as an infrared LED (Light Emitting Diode), a red color LED, a green color LED, a blue color LED, and others. These light sources are selectively used according to purposes of medical examinations.

Typical low power ophthalmic imaging devices such as Fundus cameras make use of LEDs as light source. Fig.l shows the typical ophthalmic imaging device. The typical ophthalmic device consist an objective lens (102), one or more half mirrors (Ml, M2, M3), LED light sources of different wavelength (SI, S2, S3) with collimators and a detector (104) such as an image sensor. For live mode, the ophthalmic imaging device consists of an infrared light LED source and for capturing images; the imaging device consists of a white light LED source. The two LED light sources as mentioned above requires different optical paths since the two LED light sources cannot overlap on each other. If there is a need for an internal fixation light or a red free source, an additional light source is provided. This additional light source results in an additional optical path.

An exemplary embodiment of the typical ophthalmic imaging device is shown in Fig. 2. An optic path of a ray of light emitted by at least one light source (S3) travelling from source to detector (104) is illustrated. The one or more half mirrors (Ml, M2, and M3) are placed to divert the ray from the original path. The mirrors (Ml, M2, and M3) reflect majority of incident light, but a portion of input radiation of the incident light is lost due to absorbance and scattering. The total loss of intensity of a light beam at mirror is called as attenuation. As the number of mirrors in an optical path increases, attenuations at each reflecting surface gets added and the total attenuation at the detector is considerably high. To compensate for these losses, intensity of light source (S3) should be very high, which results in high power rating of the LED.

The existing ophthalmic imaging device suffers from a number of limitations. The device consists of multiple reflectors and multiple half mirrors resulting in increase of cost of the device. The device also requires different optical paths for different sources of light. In addition, the device is not portable as the design is complex and bulky. The device is more vulnerable to environment factors such as dust and humidity. Further, the device requires high power rating due to losses from attenuation and scattering. Multiple mirrors increase complexity of the device design and reduce the precision of the device.

Therefore, there is need to overcome the above mentioned problem by providing a low power ophthalmic system and a method for obtaining the ophthalmic image.

SUMMARY OF THE DISCLOSURE

The shortcomings of the prior art are overcome and additional advantages are provided through the provision of a method and a system as described in the description.

The present disclosure relates to a low power ophthalmic imaging device using multicolored LED based light source. In an embodiment, the device of the disclosure helps in reducing number of components required for capturing an image.

The imaging device of the present disclosure substitutes for standard optical devices comprising various half mirrors and different LED light sources for ophthalmic imaging.

The ophthalmic imaging device of the present disclosure provides an advantage of cost reduction as compared to the existing devices. The overall weight of the device also is reduced, increasing portability of the device as compared to existing devices. Reduction in number of LEDs results in lower power consumption of the device as compared to exiting devices. The device of the present disclosure also supports multi spectral imaging. The quality of the illumination improves due to decrease reflections from mirrors.

In one non-limiting aspect of the present disclosure, an ophthalmic imaging device is disclosed. The device comprises a lens at one end of a first optical path and an optical detector at other end of the first optical path. The device further comprises a multicolored Light Emitting Diode (LED) at one end of a second optical path and other end of the second optical path intersecting the first optical path. A beam splitter of the device is placed at a predetermined angle at the intersection of the first and the second optical paths. The beam splitter directs the light emitted by the light source to the lens. The lens illuminates retina of an eye from the emitted light and collects the light reflected from the retina. The collected light is directed towards the optical detector by the lens. Said optical detector detects the amount of light reflected to form an ophthalmic image.

In another aspect of the present disclosure, a method for obtaining an ophthalmic image is disclosed. The method comprises emitting a light of at least one color from multicolored LED via a second optical path. Then the emitted light is directed by a beam splitter to a lens through a first optical path which illuminates retina of an eye by the received. The retina reflects the light which is collected at the lens and the collected light is passed to an optical detector through the first optical path. Finally, the collected light is processed to obtain an image of the retina to form an ophthalmic image. The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present disclosure are set forth with particularity in the appended claims. The disclosure itself, together with further features and attended advantages, will become apparent from consideration of the following detailed description, taken in conjunction with the accompanying drawings. One or more embodiments of the present disclosure are now described, by way of example only, with reference to the accompanied drawings wherein like reference numerals represent like elements and in which:

Figure 1 illustrates a conventional ophthalmic imaging device.

Figure 2 illustrates an optical path of a light ray emitted from light source of conventional ophthalmic imaging device.

Figure 3 illustrates ophthalmic imaging device with a multicolored LED in accordance with an embodiment of the present disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

In one non-limiting aspect of the present disclosure, an ophthalmic imaging device is disclosed. The device comprises a lens at one end of a first optical path and an optical detector at other end of the first optical path. The device further comprises a multicolored Light Emitting Diode (LED) at one end of a second optical path and other end of the second optical path intersecting the first optical path. A beam splitter of the device is placed at a predetermined angle at the intersection of the first and the second optical paths. The beam splitter directs the light emitted by the light source to the lens. The lens illuminates retina of an eye from the emitted light and collects the light reflected from the retina. The collected light is directed towards the optical detector by the lens. Said optical detector detects the amount of light reflected to form an ophthalmic image. In another aspect of the present disclosure, the beam splitter is selected from at least one of a half silvered mirror and a pellicle mirror.

In yet another aspect of the present disclosure, the beam splitter comprises a reflection region and a transmission region.

In still another aspect of the present disclosure, the multicolored LED emits light of wavelength in the range of 430 nm to 940 nm.

In an embodiment of the present disclosure, the optical detector is selected from at least one of image sensor and human eye.

In another aspect of the present disclosure, a method for obtaining an ophthalmic image is disclosed. The method comprises emitting a light of at least one color from multicolored LED via a second optical path. Then the emitted light is directed by a beam splitter to a lens through a first optical path which illuminates retina of an eye by the received. The retina reflects the light which is collected at the lens and the collected light is passed to an optical detector through the first optical path. Finally, the collected light is processed to obtain an image of the retina to form an ophthalmic image. In another aspect of the present disclosure, passing the collected light from the lens to the optical detector comprises transmitting the light through the beam splitter. Figure 3 illustrates ophthalmic imaging device with a multicolored LED in accordance with an embodiment of the present disclosure.

The ophthalmic imaging device comprises a lens (102) and an optical detector (104) on a first optical path (302). One end of the first optical path (302) is provided with the lens (102) and other end of the first optical path (302) comprises the optical detector (104). A single light source, i.e. a multicolored LED (304) is placed at one end of a second optical path (306). The other end of the second optical path (306) intersects the first optical path (302). In one embodiment, the second optical path (306) perpendicularly intersects the first optical path (306). In another embodiment, second optical path (306) intersects the first optical path (302) at a predetermined angle.

The multicolored LED (304) at the opening of the second optical path (306) produces light beam of desired color when it is actuated by power supply. The multicolored LED light source (304) emits light of wavelengths ranging from 430 nm (Ultra blue) to 940 nm (infrared). Further, the multicolored LEDs are operated between voltage ranges of 1.5 V to 3.5 V at 20 mA. The light beam generated by the light source passes through the second optical path (302) and falls on a beam splitter (Ml). The beam splitter (Ml) is an optical device that splits a beam of light in two. In an embodiment, a pellicle mirror can be used as a beam splitter (Ml). In another embodiment of the present disclosure, a half mirror is used as a beam splitter (Ml). The half mirror (Ml) is placed at the intersection of the first optical path (306) and the second optical path (302) at a predetermined angle. The half mirror acts as a reflecting and well as transmitting unit.

The light beam passing through the second optical path (306) is made to incident on the half mirror (Ml), which deflects the light beam to the lens (102). The lens passes the light beam to an eye in proximity of the lens. The light beam penetrates the eye and diverges to illuminate a portion of the retina of the eye. Consequently, the retina light reflected from the retina is received and collected by the lens (102). The lens (102) then transmits the collected light to the beam splitter (half mirror) through the first optical path (302). Here, the half mirror (Ml) acts as transmitting unit. The half mirror (Ml) is made of transparent material which allows reflected image of the object under observation to pass through it. The light beam transmitted from the half mirror (Ml) is transmitted to the optical detector (104). The optical detector (104) captures image of the retina based on the light reflected from the retina. This image is then used to detect eye diseases and problems.

In an embodiment, the optical detector (104) can be an image sensor configured to capture the image in digital format. The image can then be analyzed to detect any problem in the eye. In another embodiment, the optical detector (104) can be human eye, i.e. eye of doctor. The doctor will view and analyze the image for any medical condition. In another embodiment, a combination of image sensor and human eye can be used as optical detector (104). Both the human eye and the image sensor can simultaneously view and analyze the image.

The ophthalmic imaging device of the present disclosure is simple in construction.

In the present disclosure, the number of optical paths required for the light beam to travel is reduced. Only single path is used for the transferring the light beam from the LED light source to the object under observation. Hence, the device is easily portable. The multicolored LED can produce light of desired color by varying the power supply. Further, the detector (104) could be a camera which generates an image based on the light coming from lens (102). Further, the person skilled in the art would identify the type of lights that are required to be generated and the operating conditions to determine diseases or problems in the eye.

The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and devices within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

An ophthalmic imaging device comprising:

a lens at one end of a first optical path and an optical detector at other end of the first optical path;

a multicolored Light Emitting Diode (LED) at one end of a second optical path and other end of the second optical path intersecting the first optical path; and

a beam splitter placed at a predetermined angle at the intersection of the first and the second optical paths, said beam splitter directs the light emitted by the light source to the lens,

wherein the lens illuminates retina of an eye from the emitted light and collects the light reflected from the retina and directs towards the optical detector, said detector detects the amount of light reflected to form an ophthalmic image.

The device as claimed in claim 1 , wherein the beam splitter is selected from at least one of a half silvered mirror and a pellicle mirror.

The device as claimed in claim 1, wherein the beam splitter comprises a reflection region and a transmission region.

The device as claimed in claim 1, wherein the multicolored LED emits light of wavelength in the range of 430 nm to 940 nm.

The device as claimed in claim 1 , wherein the optical detector is selected from at least one of image sensor and human eye.

A method for obtaining an ophthalmic image comprising:

emitting a light of at least one color from multicolored LED via a second optical path;

directing the emitted light by a beam splitter to a lens through a first optical path;

illuminating retina of an eye by the light received by the lens, wherein said retina reflects the light; collecting the light reflected by retina at the lens and passing the collected light to an optical detector through the first optical path; and

processing the collected light to obtain an image of the retina to form an ophthalmic image.

The method as claimed in claim 6, wherein passing the collected light from the lens to the optical detector comprises transmitting the light through the beam splitter.