Progressive Ophthalmic Lens Determination via Sagittal Plane Shift
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Solution Overview
Problem
Existing methods for determining progressive ophthalmic lenses do not adequately account for the shift in a wearer's sagittal plane, leading to suboptimal vision comfort and field of view, as they rely on average positions rather than individual eye-head behavior and movement strategies.
Innovation Solution
A method that measures the shift in the wearer's sagittal plane relative to the standard sagittal plane and uses these measurements to optimize the determination of progressive multifocal lenses, adjusting target values and meridian deformation to improve optical calculation and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lens determination is based on average wearer position and standard sagittal plane, then the manufacturing process is simple and standardized, but the vision comfort and field of view are suboptimal for individual wearers
Solution Approach 1:
The patent performs preliminary measurement of the wearer's sagittal plane shift and eye-head movement strategy before lens fabrication. This preliminary action allows the lens to be pre-designed and optimized for the individual wearer's specific anatomical and behavioral characteristics, thereby improving vision comfort without requiring complex adjustments during wear.
Solution Approach 2:
The patent changes the determination parameters from standard average values to individualized parameters including the wearer's specific sagittal plane shift, eye-head movement strategy, and viewing habits. This parameter customization enables the lens to be optimized for the individual wearer's unique optical and behavioral characteristics, resolving the contradiction between standardization and personalization.
2Area of stationary object
If the lens is optimized for individual eye-head behavior and sagittal plane shift, then the field of view and binocular fusion are improved, but the measurement and determination process becomes more complex
Solution Approach 1:
The patent introduces an intermediary measurement system that indirectly captures sagittal plane shift and eye-head movement strategy through observable parameters such as head position, eye position, and viewing angle. This intermediary approach simplifies the measurement process by translating complex anatomical and behavioral parameters into measurable quantities that can be captured during routine optometric examinations.
Solution Approach 2:
The patent incorporates feedback mechanisms where the measured sagittal plane shift and eye-head movement strategy are used to iteratively refine the lens design. This feedback loop allows the lens determination process to continuously improve accuracy by comparing predicted optical performance with actual wearer feedback, thereby expanding the field of view while managing measurement complexity through iterative optimization.
3Ease of operation
If the lens design accounts for wearer's lateral vision strategy and head movement, then the oculomotor strategy becomes more natural, but the optimization calculation becomes more complex
Solution Approach 1:
The patent segments the optical calculation into distinct functional zones corresponding to different viewing scenarios (distance, intermediate, near vision) and different head/eye movement strategies. This segmentation allows the complex optimization to be broken down into manageable sub-problems, each optimized for specific viewing conditions, thereby simplifying the overall calculation while maintaining natural oculomotor strategy.
Solution Approach 2:
The patent incorporates dynamic elements into the lens design by accounting for the wearer's actual head and eye movement patterns rather than assuming static positioning. This dynamic approach allows the lens to be optimized for the wearer's natural oculomotor strategy, improving ease of operation while managing calculation complexity through physics-based optical models that simulate dynamic viewing conditions.
Data Source
AI summary
The invention relates to the determination of a pair of ophthalmic lenses, by measurement of the sagittal plane shift of the wearer for close vision with relation to the standard sagittal plane. Optimisation targets are then chosen as a function of the measured shift. The lenses are determined by optimisation with the chosen targets. Lenses are thus obtained with which the field of close vision is symmetrical with relation to the medial line as perceived by the wearer. A wearer with a displaced sagittal plane thus has a greater close vision field which facilitates binocular vision and increases acuity.