Fusional Vergence Thresholds for Progressive Lens Acceptance
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Solution Overview
Problem
There is a need for a reliable and simple method to determine the acceptance of progressive addition lenses by wearers, as existing methods are not exhaustive or very reliable, particularly for presbyopic wearers with conditions like strabismus, amblyopia, anisometropia, or convergence insufficiency.
Innovation Solution
A method involving the measurement of fusional vergence parameters, such as the rate of phoria adaptation and vergence facility, where the values are compared to predetermined thresholds to assess the probability of acceptance, using equations like FCP = FPM - IPM * T for phoria adaptation and determining fixations per minute for vergence facility, with specific distances and environments to reduce variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clinical indicators like strabismus, amblyopia, anisometropia, or convergence insufficiency are used to predict non-acceptance of progressive addition lenses, then some prediction capability is achieved, but the method is not exhaustive and lacks reliability
Solution Approach 1:
The patent changes the predictive parameter from complex clinical indicators (strabismus, amblyopia, anisometropia) to a single quantitative parameter: fusional vergence measured in prism diopters. This parameter change simplifies the assessment method while improving reliability, as fusional vergence provides a direct numerical measure of the wearer's ability to adapt to progressive lenses.
Solution Approach 2:
The patent replaces the complex clinical assessment system (multiple clinical indicators requiring professional judgment) with a simpler optometric measurement system based on fusional vergence testing. This substitution uses standard optometric equipment and procedures to obtain an objective quantitative measure, replacing the subjective and incomplete clinical indicator approach.
2Reliability
If multiple clinical indicators are assessed to determine lens acceptance, then prediction coverage is improved, but the assessment becomes more complex and less reliable
Solution Approach 1:
The patent extracts the essential predictive capability from the complex set of clinical indicators and isolates it into a single key parameter: fusional vergence. By taking out only the most critical aspect of visual function relevant to progressive lens adaptation, the method achieves high reliability while maintaining simplicity in assessment procedures.
3Measurement precision
If fusional vergence parameters are measured and compared to threshold values, then the accuracy of acceptance determination is improved, but the measurement and calculation process becomes more complex
Solution Approach 1:
The patent performs preliminary measurements of fusional vergence at multiple distances (near, intermediate, far) and calculates adaptation rates before making the acceptance determination. By gathering all necessary data and performing calculations in advance, the method achieves high measurement precision while streamlining the final decision-making process, as the complex work is已完成 in the measurement and calculation phase.
Data Source
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AI summary
Method for determining the acceptance of progressive addition lenses of a wearer, the method comprising: a fusional vergence parameter providing step during which at least one fusional vergence parameter representing the fusional vergence of the wearer is provided, an acceptance determining step during which the value of the at least one fusional vergence parameter is compared to a predetermined threshold value so as to determine the probability of acceptance of progressive addition lens of the wearer.