Optotype-Based Dioptric Power Testing for Astigmatism Without Overcorrection
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Solution Overview
Problem
Existing methods for determining dioptric power in ophthalmic lenses are cumbersome, prone to overcorrection, and lack accuracy in assessing astigmatic power and axis, particularly in subjective and objective tests, and large-scale automation solutions are inconvenient.
Innovation Solution
A dioptric power determination method that involves setting a target eyesight value, allowing subjects to view optotypes in various directions while wearing or not wearing a test lens, and estimating dioptric power based on responses to determine the desired lens power accurately without overcorrection, using a subjective method with probability functions and optimization calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an autorefractometer is used for objective test, then the dioptric power can be determined quickly in a few seconds, but the measurement is affected by mechanical near-sightedness (accommodation phenomenon) causing overcorrection
Solution Approach 1:
The patent introduces an optotype recognition task as an intermediary mechanism to shift the subject's visual focus from near (causing accommodation) to far (eliminating accommodation). By requiring the subject to identify the direction of optotypes at a distance, the measurement process naturally prevents the accommodation phenomenon that plagues traditional autorefractometry, thereby maintaining measurement speed while eliminating overcorrection.
Solution Approach 2:
The patent replaces the purely mechanical/optical autorefractometer system with a hybrid system that incorporates subject response (optotype direction identification). This substitution transforms the measurement from a passive optical reflection method to an active subject-participation method, where the subject's visual fixation on distant optotypes naturally controls accommodation state, thereby improving measurement accuracy without sacrificing efficiency.
2Measurement precision
If a subjective eyesight test is performed to include astigmatic power, then accurate vision correction can be achieved, but many procedures are required making the determination method troublesome and complex
Solution Approach 1:
The patent merges the astigmatic power determination and astigmatic axis determination into a single integrated test procedure. By using optotypes with gaps oriented in different directions and requiring the subject to identify the gap direction, the method simultaneously captures information about both the magnitude and orientation of astigmatism, eliminating the need for separate Jackson cross-cylinder procedures and simplifying the overall test workflow.
Solution Approach 2:
The patent changes the test parameter from traditional endpoint-based subjective judgment to a probabilistic model based on multiple optotype direction responses. By collecting responses to optotypes with gaps in various directions and analyzing the distribution of correct answers, the system calculates astigmatic power and axis through optimization, transforming a complex multi-step procedure into a more streamlined data-driven approach.
3Measurement precision
If traditional eyesight test procedures are used, then comprehensive vision assessment can be performed, but the subject becomes tired and the visual perception state is altered during the test
Solution Approach 1:
The patent applies partial action by using a limited set of optotype directions (six specific directions) rather than attempting to test all possible orientations. This selective sampling approach, combined with the probabilistic optimization model, achieves accurate astigmatic parameter determination with fewer test stimuli, thereby reducing test duration and preventing subject fatigue while maintaining measurement precision.
Data Source
AI summary
[Abstract] A dioptric power determination method is provided that is capable of accurately calculating not only the lens diopter power but also both the astigmatic power and the astigmatic axis according to a convenient subjective method and that is capable of reflecting a halfway test result on the final dioptric power without fear of the occurrence of overcorrection.[Solution] The method includes the steps of setting a target value of the eyesight in a state in which a subject has been subjected to refractive-error correction; allowing the subject to watch a plurality of optotypes facing various different directions in a state of wearing a test lens or in a naked-eye state while regarding the target value as target eyesight; asking the subject to answer the direction of the optotype; if a result in which a correct answer and an incorrect answer, or a correct answer and an indistinguishable answer, or a correct answer, an incorrect answer, and an indistinguishable answer coexist is obtained, estimating a dioptric power by which the subject visually perceives the optotype with a fixed predetermined probability in all directions in a circumferential direction of the optotype corresponding to the target eyesight on a basis of a relationship between a response and a dioptric power corresponding to the response; and determining the dioptric power of the ophthalmic lens of the subject on a basis of an estimation result obtained by estimating the dioptric power.