Progressive Lens Design Using Axial Length Calculation
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Solution Overview
Problem
Current progressive multifocal ophthalmic lenses are not adequately personalized to meet the unique needs of individual wearers, as they rely on complex and costly measurements of the axial length and center of rotation of the eye, which are difficult to obtain and do not directly account for the wearer's specific visual comfort requirements.
Innovation Solution
A method for determining a progressive ophthalmic lens that uses the wearer's prescribed far-vision power and near-vision power addition to calculate the axial length and center of rotation of the eye, allowing for the optimization of power and astigmatism defect fields and gradients, thereby improving visual comfort without the need for precise measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precise measurements of axial length and center of rotation are performed to personalize progressive lenses, then visual comfort is improved, but measurement complexity and cost increase
Solution Approach 1:
The patent uses optical copying techniques where the wearer's eye is imaged through the lens onto a retinal target. By capturing and analyzing the reflected light pattern (copy of the eye), the system derives axial length and center of rotation information without direct physical measurement of these biometric parameters. This copying approach simplifies the measurement process while maintaining personalization accuracy.
Solution Approach 2:
The patent introduces an optical intermediary system consisting of the progressive lens itself and a retinal target. Instead of measuring eye biometrics directly, the system uses the lens-optical path-retina combination as an intermediary to indirectly obtain the necessary biometric information through optical reflections and refractions. This mediator approach converts complex biometric measurement into a simpler optical observation task.
2Ease of manufacture
If traditional optimization methods based on average wearer characteristics are used, then manufacturing simplicity is maintained, but lens performance for individual wearers deteriorates
Solution Approach 1:
The patent enables dynamic adjustment of lens optimization parameters based on individually measured biometric data. By changing the parameters (axial length, center of rotation, pupillary distance) for each wearer rather than using fixed average values, the system personalizes the progressive lens design while maintaining manufacturing feasibility through digital parameter input into existing lens design software.
Solution Approach 2:
The patent performs preliminary measurement and analysis of the wearer's biometric parameters before the lens manufacturing process. By obtaining axial length, center of rotation, and other biometric data in advance through the optical measurement system, the lens can be optimized specifically for that wearer before production begins, ensuring individualized performance without complicating the actual manufacturing process.
3Reliability
If lens position in the frame is precisely measured and considered in optimization, then visual comfort is improved, but measurement difficulty and time increase
Solution Approach 1:
The patent merges the measurement of lens position with the measurement of eye biometrics into a single integrated optical measurement process. By combining these measurements that are currently performed separately, the system reduces overall measurement time and complexity while obtaining both lens positioning data and eye parameter data simultaneously through the same optical path and imaging system.
Data Source
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AI summary
A method for the determination of a progressive ophthalmic lens for a given wearer comprises the stages of: - determining the axial length (LA) of the wearer's eye, - determining an ergorama associating a sight point with each direction of viewing under wearing conditions. - determining power and resulting astigmatism defect targets for each direction of viewing under wearing conditions, the targets being a function of the axial length of the wearer's eye. - calculating the power required on the lens for each direction of viewing by successive iterations in order to obtain the target power defect and the target resulting astigmatism.