Astigmatic Spectacle Lens with Multi-Gaze Axis Correction
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Solution Overview
Problem
Existing methods for manufacturing spectacle lenses to correct astigmatism do not provide fully satisfying results, especially for customers requiring corrections of more than 1 or 2 diopters, as they fail to account for the rotation of the eye and varying directions of gaze, leading to incomplete astigmatic correction across the lens surface.
Innovation Solution
A method that measures the axis direction of astigmatism for multiple directions of gaze, determines the primary orientation of the eye using Listing's Law, and computes the shape of the spectacle lens surface to ensure accurate astigmatic correction across all directions of gaze by simulating light rays traversing the lens for various gaze positions, allowing for different astigmatic powers in different portions of the lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a pure toric lens surface is used to correct astigmatism, then the manufacturing process is simple, but the astigmatic correction is incomplete for directions of gaze other than the reference point
Solution Approach 1:
The patent applies local quality by making different portions of the lens surface have different optical properties. The lens surface is divided into multiple zones corresponding to different directions of gaze, with each zone having locally optimized curvature and astigmatic power to correct for the specific axis direction required at that viewing angle, rather than using a uniform toric surface throughout.
Solution Approach 2:
The patent introduces dynamic characteristics to the lens design by accounting for the dynamic nature of eye movement. The lens surface is designed to provide varying astigmatic correction depending on the direction of gaze, effectively making the optical properties adaptive to the user's viewing direction, similar to how a dynamic system adjusts to changing conditions.
2Manufacturing precision
If the lens surface is designed to correct astigmatism at multiple directions of gaze, then the astigmatic correction accuracy is improved, but the lens surface complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the lens surface into multiple functional zones, each responsible for correcting astigmatism in a specific direction of gaze. This segmentation allows the complex correction task to be distributed across different regions of the lens, with each region having optimized parameters for its specific viewing direction, making the overall complex function manageable through localized simpler functions.
3Manufacturing precision
If measurements are taken for more than three directions of gaze, then the astigmatic correction accuracy is improved, but the measurement time increases
Solution Approach 1:
The patent applies partial or excessive action by measuring astigmatic parameters at more directions of gaze than the minimum three required for mathematical determination. This excessive measurement approach provides redundant data that improves the accuracy and reliability of the lens surface computation, allowing for better optimization of the multi-directional correction while the computational algorithm efficiently processes the additional measurements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides improved astigmatic correction by ensuring that the lens compensates for astigmatism across the entire surface, reducing aberrations and enhancing the accuracy of the correction, particularly for higher astigmatic powers, and optimizing the lens design for specific wearing conditions.
Implementation Method 1
A solution can be achieved by designing the spectacle lens such that bundles of light rays which traverse the spectacle lens for different directions of gaze experience axis directions of the astigmatic effect corresponding to those axis directions of the astigmatism of the eye
Data Source
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AI summary
A method of manufacturing a spectacle lens providing at least an astigmatic correction for a customer comprises: - measuring a direction of an axis of an astigmatism of an eye for each of different directions of gaze of the eye; - determining a position of the spectacle lens relative to the customer's eye; and - computing a shape of a surface of the spectacle lens based on the determined position of the spectacle lens relative to the eye and the measured directions of the axis of the astigmatism; wherein the measuring of the direction of the axis of the astigmatism of the eye is performed for more than 15 mutually different directions of gaze, wherein the calculating of the shape of the surface of the spectacle lens includes a simulation of light rays traversing the eye and the spectacle lens for a plurality of directions of gaze of the eye, and wherein the direction of the astigmatism of the eye for the plurality of directions of gaze is determined by interpolation of the measured directions of the axis of the astigmatism of the eye.