NL2035161B1

NL2035161B1 - Method to measure variable lens power

Info

Publication number: NL2035161B1
Application number: NL2035161A
Authority: NL
Inventors: Christiaan Rombach Michiel
Original assignee: Akkolens Int B V
Priority date: 2022-07-01
Filing date: 2023-06-23
Publication date: 2024-03-25
Also published as: NL2035161A

Abstract

This document discloses a method and apparatus for measuring variable lens power. During movement of an illuminated visual target along the optical axis of the 5 eye the variable optical power of the lens of the eye as well as the diameter of the pupil of the eye are dynamically measured. The illumination of the visual target is continually adjusted such that the diameter of the pupil of the eye remains at a constant diameter. The method prevents that changes in pupil diameter affect the required variable lens power for sharp vision at near distances.

Description

Method to measure variable lens power

The variable ocular optical power of a lens in the eye, henceforth: ‘variable lens power’, being the variable lens power of the natural lens or an artificial intraocular lens, for example, an accommodating intraocular lens, can be objectively measured by dynamically, meaning measuring the variable lens power multiple times or continuously while stimulating the eye to change the variable lens power, to accommodate, by moving a visual target, for example an illuminated visual target, along the optical axis towards or away from the eye.

However, the diameter of the pupil of the eye provides extended depth of field. The degree of extended depth of field increases with a decrease in the diameter of the pupil. An increased extended depth of field decreases the need for increased variable lens power for sharp vision at near distances. Stimulating accommodation during such measurements while fixing the pupil diameter a constant, preferably predetermined, diameter provides most accurately the ability of the variable lens to increase in optical power. The method disclosed in the present document thus provides for measurements of variable lens power independent from the pupil diameter.

The method requires measurement of the diameter of the pupil simultaneously with said measurement of variable lens power. Such combination of measurements can be obtained from several ophthalmology apparatus, for example, but not restricted to, from the WAM5500 Binocular Accommodation Auto Refractor (Grand-Seiko,

Japan) which apparatus provides two continuous digital data streams with one on variable lens power (in diopters), and one on pupil diameter {in millimeters).

The method for measuring the variable lens power comprises the steps of (a) maving an illuminated visual target along the optical axis of the eye and (b) measure, during the movement of the target, the variable lens power and the diameter of the pupil of the eye and (c) adjust the illumination of the visual target such that the diameter of the pupil of the eye remains at a constant, preferably predetermined, diameter.

The illumination of the target can be adjusted by adjusting the illumination power of a spotlight targeting the visual target, or, alternatively, adjusting the illumination power of the target, for example, adjusting the illumination of a digital screen, or, alternatively, adjusting the ambient illumination while keeping the target under constant illumination.

An apparatus for measuring the lens power in an eye according to the foregoing method can comprise (a) a first optical device for measuring the variable lens power and (b) a second optical device for measuring the pupil diameter of the eye, simultaneously with measuring the variable lens power and (c} a moving visual target, to focus the eye and {(d) an illumination device, for illuminating the visual target and (e) a controller for adjusting the illumination of the illumination device depending on the measured diameter of pupil of the eye with the controller arranged to adjust the illumination of the illumination device such that the pupil of the eye remains at a constant predetermined diameter. The first and second optical devices can be integrated in a single device, in a single housing, or, alternatively, can be independent devices, in independent housings.

Also, the first optical device, providing objective, as reported by the apparatus, measurement of variable lens power can be eliminated and replaced by subjective measurement of variable lens power, for example, a standard ophthalmological reading chart with adjusted illumination with the degree of illumination adjusted for measured pupil size. In such arrangement the variable lens power can be derived from the subjective, as reported by the patient, chart-reading results.

Thus, said method for measuring variable lens power, the optical power of a lens in an eye, comprises moving an illuminated visual target along the optical axis of the eye, and, measuring, during the movement of the target, the variable lens power and measuring the diameter of the pupil of the eye, and, adjusting the illumination of the visual target such that the diameter of the pupil of the eye remains at a constant diameter wherein the illumination of the visual target can be adjusted by adjusting the illumination power of a spotlight targeting the visual target, or, alternatively, by adjusting the illumination power of the target, or, alternatively, by adjusting ambient illumination, and, with an a apparatus for measuring the variable lens power of a lens in an eye with the apparatus comprising a first optical device for measuring the variable lens power, and a second optical device for measuring the pupil diameter of the eye, simultaneously with measuring the variable lens power while moving a visual target to focus the eye at at least one distance, and, an illumination device, for illuminating the visual target, and a digital controller, for adjusting the illumination of the illumination device depending on the measured diameter of pupil of the eye wherein the controller is arranged to adjust the illumination of the illumination device such that the pupil of the eye remains at a constant diameter.

Claims

Conclusions

1. Method for measuring variable lens power, the variable optical power of a lens in an eye, the method comprising the steps of:

a. moving an illuminated visual target along the optical axis of the eye;

b. measuring the ocular lens power and the diameter of the pupil of the eye during the movement of the target;

c. adjusting the illumination of the visual target so that the diameter of the pupil of the eye remains at a constant diameter.

The method of claim 1, wherein illumination of the visual target is adjusted by adjusting the illumination power of a spotlight directed at the visual target.

The method of claim 1, wherein exposure of the visual target is adjusted by adjusting the exposure power of the visual target.

The method of claim 1, wherein relative illumination of the visual target is adjusted by adjusting ambient illumination.

5. Apparatus for measuring the variable lens power of a lens in an eye with the device comprising:

a. a first optical device for measuring the variable lens power;

b. a second optical device for measuring the pupillary diameter of the eye simultaneously with measuring the variable lens power;

c. a moving visual target to focus the eye at at least one distance;

d. an illumination device, for illuminating the visual target;

e. a digital controller, for adjusting the exposure of the lighting device depending on the measured diameter of the pupil of the eye, wherein the controller is designed to adjust the exposure of the lighting device in such a way that the pupil of the eye remains at a constant diameter . 5