Toric Contact Lens Stabilization Zones for Rotation Control
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Solution Overview
Problem
Contact lenses for astigmatism correction often rotate and deviate due to blinking, leading to poor correction performance and blurred vision.
Innovation Solution
A contact lens design featuring an optical zone surrounded by a peripheral zone with symmetric stabilization zones that gradually thicken, each with specific elevation boundaries and angles, ensuring rapid positioning and attachment to the eye, reducing foreign body sensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a contact lens for astigmatism correction is designed with cylindrical or aspheric characteristics, then vision correction performance is improved, but the lens rotates and deviates during wear, causing blurred vision
Solution Approach 1:
The contact lens is segmented into distinct functional zones: an optical zone for vision correction and a peripheral zone with stabilization zones for orientation control. The stabilization zones are further divided into upper and lower portions with specific elevation boundaries, creating a multi-segmented structure that independently addresses both correction and stability requirements
Solution Approach 2:
Different zones of the contact lens are assigned different local qualities and functions. The optical zone maintains aspheric characteristics for vision correction, while the peripheral zone incorporates stabilization zones with specific thickness variations (0.15-0.35mm) and elevation boundaries at defined angles (+55° to +75° and -55° to -75°) to control lens orientation. This local differentiation allows the lens to simultaneously achieve correction performance and rotational stability
2Stability of the object's composition
If existing stable structures are added to the contact lens, then rotation and deviation are reduced, but the lens design complexity increases
Solution Approach 1:
The stabilization function is merged into the peripheral zone structure itself rather than being implemented as a separate mechanical stabilization mechanism. The stabilization zones are integrated with the lens periphery, using thickness variations and elevation boundaries within the existing lens geometry to achieve orientation control, thereby reducing overall design complexity
Solution Approach 2:
The stabilization is achieved through controlled parameter changes in the peripheral zone, specifically thickness variations (0.15-0.35mm) and strategically positioned elevation boundaries at defined angular locations. These parameter modifications create stable orientation without requiring complex mechanical structures, maintaining design simplicity while achieving the desired stability effect
Data Source
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AI summary
A contact lens (1) comprises an optical zone (10) and a peripheral zone (20). The optical zone (10) is used for vision correction. The peripheral zone (20) surrounds the optical zone (10). The optical zone (10) and the peripheral zone (20) jointly define a geometric center (O) and a horizontal axis (X) passing through the geometric center (O). Two stabilization zones (30) symmetrically arranged relative to the geometric center (O) are formed in the peripheral zone (20). These stabilization zones (30) gradually thicken relative to a base curved surface (21) of the peripheral zone (20).