Ophthalmic Lens Zone Interpolation for Thickness Reduction
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Solution Overview
Problem
Conventional ophthalmic lenses with high curvature or high-prescription lenses often have significant edge and center thickness issues, leading to increased weight, unsightly appearance, and difficulty in fitting, especially for progressive multifocal lenses, which compromise wearer comfort and visual aesthetics.
Innovation Solution
An ophthalmic lens design featuring a first face with a maximum radius of curvature and a complex second face with an optically useful central zone, a peripheral zone, and a connection zone, where the maximum radius of curvature of the peripheral zone is between the first and central zones, optimized using an interpolation function to minimize thickness and improve comfort by adjusting the relative positioning of the central and peripheral zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lens has high curvature or high-prescription to correct vision defects, then the optical correction performance is improved, but the edge and center thickness increase significantly
Solution Approach 1:
The lens surface is segmented into multiple zones (central optically useful zone and peripheral zone) with different curvature characteristics. The central zone maintains high curvature for optical correction, while the peripheral zone has reduced curvature to minimize edge thickness, resolving the contradiction between optical performance and thickness reduction.
Solution Approach 2:
Different regions of the lens are assigned different local qualities: the central zone has high curvature optimized for vision correction, while the peripheral zone has lower curvature optimized for thickness reduction. This local differentiation allows simultaneous optimization of both optical performance and aesthetic appearance.
2Weight of moving object
If the lens thickness is reduced to improve aesthetics and comfort, then the weight and appearance are improved, but the optical performance in the peripheral zone deteriorates
Solution Approach 1:
The lens is segmented into a central optically useful zone where high optical performance is maintained and a peripheral zone where thickness is reduced. By separating these functions to different zones, the lens achieves both weight reduction and preserved optical performance in the critical central viewing area.
Solution Approach 2:
The lens applies local quality differentiation by maintaining high curvature and optical precision in the central zone while reducing curvature in the peripheral zone. This allows the lens to be lighter and more aesthetic without compromising the optical performance where the wearer actually looks through the lens.
3Stability of the object's composition
If the lens is designed with a connection zone between central and peripheral zones, then the manufacturing complexity increases, but the transition smoothness and optical continuity are improved
Solution Approach 1:
A connection zone is introduced as an intermediary region between the central and peripheral zones. This intermediate zone provides a gradual transition of curvature, ensuring optical continuity and eliminating abrupt changes. While this adds some design complexity, it is necessary to maintain optical quality and avoid visual disturbances for the wearer.
Data Source
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AI summary
The invention relates to a method for determining an ophthalmic lens by optimisation, that comprises the steps of: defining a starting surface for a side of the lens having a central area (15) with a diameter Dini and a peripheral area (17) with a diameter Drac; selecting an interpolation formula; optimising the lens by applying the interpolation formula to the central (15) and peripheral (17) areas in order to define an interpolated surface having a seam area (16), the interpolated surface minimising a merit function (FM) for different relative altitudes of the peripheral area (17) relative to the central area (15). The invention reduces the thickness of the lens without increasing the obliquity defects for a good visual comfort of the wearer.