Ophthalmic Focus Control for Fundus Reflection Detection
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Solution Overview
Problem
Existing ophthalmic apparatuses struggle to accurately detect fundus reflection light due to turbidity in intermediate light projection bodies like cataracts, leading to erroneous detection of internal reflections.
Innovation Solution
An ophthalmic apparatus with a measurement optical system, focus adjustment unit, and control unit that captures fundus reflection light as a pattern image, adjusts the focus position of the imaging element, and distinguishes between fundus and internal reflections using threshold values and stored distinction information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fundus reflection light is detected using a measurement optical system, then eye characteristic measurement is enabled, but detection accuracy deteriorates when intermediate light projection bodies are turbid
Solution Approach 1:
The imaging element is made movable along the optical axis through a focus adjustment unit, enabling dynamic focus position changes. This allows the system to adapt to varying eye conditions (emmetropic, myopic, hyperopic) and maintain accurate fundus reflection light detection even when intermediate light projection bodies are turbid, thereby resolving the contradiction between measurement precision and reliability under different conditions.
2Productivity
If measurement is performed through turbid intermediate light projection bodies, then eye characteristic measurement is attempted, but internal reflection light is erroneously detected instead of fundus reflection light
Solution Approach 1:
By dynamically adjusting the focus position of the imaging element along the optical axis, the system can selectively focus on the fundus reflection light while keeping internal reflection light out of focus. This dynamic focusing capability enables accurate distinction between fundus and internal reflection light, preventing erroneous detection and maintaining measurement capability even through turbid media.
3Measurement precision
If focus position is fixed, then device complexity is reduced, but detection accuracy of fundus reflection light deteriorates in eyes with different refractive conditions
Solution Approach 1:
A focus adjustment unit is introduced that moves the imaging element along the optical axis based on refractive error information. This dynamic adjustment mechanism allows the system to accommodate different eye conditions (emmetropic, myopic, hyperopic) while maintaining accurate fundus reflection light detection. The added complexity is justified by the significant improvement in measurement precision across diverse patient populations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the detection of fundus reflection light, reducing erroneous detections and improving measurement accuracy even in conditions with turbid intermediate light projection bodies.
Implementation Method 1
measures the eye characteristic by capturing, as a pattern image, fundus reflection light of measurement light emitted from the measurement light source using the imaging element
Data Source
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AI summary
The present invention addresses the technical problem of providing: an ophthalmic device that can suitably detect fundus-reflected light; and an ophthalmic device control program. Provided is an ophthalmic device for measuring eye characteristics of an eye under examination, said ophthalmic device characterized by comprising: a measurement optical system that has a measurement light source and an imaging element, and that measures said eye characteristics by performing imaging with the imaging element, using, as a pattern image, fundus-reflected light of measurement light emitted from the measurement light source; a focus adjustment means that moves a focus position of the imaging element in the optical axis direction of the imaging element; and a control means that controls the focus adjustment means to move the focus position if the pattern image is not detected from a measurement image obtained with the imaging element.