Ophthalmic Lens Power Calculation With Head Position Compensation
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Solution Overview
Problem
Existing methods for determining refractive power values for ophthalmic lenses do not adequately account for the position of the individual's head during subjective refraction tests, leading to inaccuracies in lens corrections.
Innovation Solution
A method and system that incorporate the precise positioning of the individual's head during subjective refraction tests by measuring and recording parameters such as eye rotation centers, yaw and roll angles, and frame positions to accurately determine and manufacture ophthalmic lenses that provide the desired refractive power when worn.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional subjective refraction methods are used without accounting for head position, then the refraction test can be performed quickly and simply, but the accuracy of the refractive power determination deteriorates
Solution Approach 1:
The patent introduces an intermediary computational process that transforms the refraction apparatus measurements and head position data into accurate lens prescriptions. This intermediary calculation layer reconciles the simple measurement process with the need for high accuracy by mathematically compensating for head position effects, rather than requiring complex real-time measurement equipment.
Solution Approach 2:
The patent replaces complex mechanical measurement systems with computational methods. Instead of using sophisticated equipment to directly measure the complex interactions between head position and refraction, the system uses standard refraction measurements combined with head position data and computational algorithms to achieve high accuracy.
2Manufacturing precision
If head position parameters are measured and incorporated into lens determination, then the accuracy of lens correction improves, but the complexity of the manufacturing process increases
Solution Approach 1:
The patent applies preliminary action by measuring and recording head position parameters during the refraction test phase, before the lens manufacturing process begins. This allows the manufacturing system to receive pre-processed data that already accounts for head position effects, simplifying the actual manufacturing process while maintaining high precision.
Solution Approach 2:
The patent transforms the refraction measurements by applying parameter changes that compensate for head position effects. The system modifies the refraction values based on measured head position parameters (yaw, roll, pitch angles and distances), converting them into adjusted parameters that directly guide lens manufacturing with high precision.
3Measurement precision
If the refraction apparatus is positioned at a standard distance from the eye, then the measurement process is simplified, but accuracy deteriorates when the individual's head position varies from the standard
Solution Approach 1:
The patent implements feedback by measuring the actual head position parameters during the refraction test and using this information to adjust and correct the refraction measurements. The system continuously monitors head position (distances and angles) and feeds this information back into the calculation process to compensate for deviations from standard positioning, maintaining high accuracy without complicating the measurement procedure.
Data Source
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AI summary
A method of determining a refractive power value characterising an ophthalmic lens for correction of an individual's eye ametropia comprises the following steps: - obtaining first data representative of a refraction value and second data (D1, D2) representative of a position of the individual's head with respect to a refraction apparatus when said refraction value was determined; - determining said refractive power value as a function of said first data and of a relative position, derived said second data (D1, D2), of the refraction apparatus with respect to a centre of rotation (O) of said eye when the refraction value was determined. A corresponding electronic device is also proposed.