Binocular Eye Position Measurement Using Corneal Reflection Tracking
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Solution Overview
Problem
Conventional ophthalmic apparatuses struggle to accurately measure and grasp the state of a subject's eye, particularly in cases of strabismus or phoria, as they fail to effectively switch between binocular and monocular vision and accurately determine eye position.
Innovation Solution
An ophthalmic apparatus that allows simultaneous binocular measurement of both eyes with adjustable measurement heads, incorporating multiple optical systems for objective and subjective testing, including gaze direction detection through corneal bright spots and pupil centers, and displays eye position information on a screen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ophthalmic apparatus measures eye position using visible light switching between binocular and monocular vision, then eye position abnormalities can be detected, but the measurement precision is insufficient for accurately grasping strabismus or phoria conditions
Solution Approach 1:
The patent replaces the mechanical/optical switching system between binocular and monocular vision with an image processing-based detection system. The line-of-sight direction detection unit uses image processing to analyze the relative positions of corneal bright spots and pupil centers captured by imaging elements, eliminating the need for physical switching mechanisms while achieving more precise and continuous measurement of eye position abnormalities.
Solution Approach 2:
The patent uses image copying and processing techniques by capturing optical images of the eye and creating digital representations. The line-of-sight direction detection unit processes these copied images to determine eye position, allowing for more accurate analysis of strabismus and phoria conditions without requiring direct physical manipulation of the optical path.
2Productivity
If the ophthalmic apparatus uses multiple optical systems for simultaneous binocular measurement, then measurement efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent combines the imaging functions for both eyes into a unified detection system. The imaging elements and line-of-sight direction detection unit process images from both subject eyes simultaneously through integrated image processing, allowing efficient binocular measurement while reducing overall system complexity compared to separate independent measurement systems for each eye.
Solution Approach 2:
The imaging elements and processing units are designed to serve multiple functions: capturing corneal bright spots, detecting pupil centers, and determining line-of-sight directions for both eyes. This multi-functional design improves measurement efficiency by using the same hardware components for multiple measurement tasks rather than requiring separate dedicated systems.
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
Enables precise detection and display of eye conditions such as strabismus or phoria, facilitating accurate assessment of eye positions and characteristics.
Implementation Method 1
gaze direction detection through corneal bright spots and pupil centers
Implementation Method 2
optotype projection system that presents an optotype to the subject eye
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An ophthalmic apparatus includes an image acquisition unit (159) configured to acquire an anterior segment image (E') of a subject eye (E), an optotype projection system (140) configured to present an optotype to the subject eye (E) in at least two presentation positions different from each other, and a line-of-sight direction detection unit (26) configured to extract a feature point from the anterior segment image (E') that has been acquired by the image acquisition unit (159) when the optotype has been presented in each of the at least two presentation positions, detect positional information on the anterior segment image (E') of the feature point that has been extracted, and detect a line-of-sight direction of the subject eye (E) on a basis of the positional information.