Toric Contact Lens Stabilization Zones for Asymmetric Eyelid Bias
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Solution Overview
Problem
Toric contact lenses often experience misalignment due to asymmetric eyelid shapes, which can lead to suboptimal vision correction for astigmatic patients.
Innovation Solution
The design incorporates stabilization zones with varying thickness profiles and contour lines that are oriented to match a target eyelid margin shape, minimizing the effect of asymmetric eyelid bias and maintaining rotational orientation with the principal meridians of the eye.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If stabilization zones are designed to contact asymmetric eyelid margins, then the lens can rotate to align with the eyelid shape, but the corrective powers become misaligned with the principal meridians of the eye
Solution Approach 1:
The patent applies asymmetry by designing stabilization zones with contour lines that are intentionally non-concentric to the lens periphery. This asymmetric configuration allows the lens to interact with asymmetric eyelid margins while maintaining proper alignment with the principal meridians, resolving the contradiction between achieving rotational stability and maintaining alignment precision.
2Ease of operation
If the contact lens is made soft and flexible to wrap around the cornea, then comfort is improved, but the lens tends to rotate on the eye
Solution Approach 1:
The patent segments the lens periphery into multiple stabilization zones with specific contour line configurations. This segmentation allows the soft lens to maintain comfort while the distributed stabilization zones work together to prevent rotation, resolving the contradiction between comfort and orientation stability.
Solution Approach 2:
The patent applies local quality by creating specific stabilization zones with varying thickness profiles and contour line configurations at the lens periphery, while keeping the central optic zone soft and flexible. This localized structural differentiation enables the lens to be comfortable yet rotationally stable.
3Stability of the object's composition
If the stabilization zones have thicker regions to provide stabilization force, then rotational orientation is maintained, but the lens thickness varies more across the periphery
Solution Approach 1:
The patent applies local quality by concentrating thickness variations specifically in the stabilization zones at the lens periphery, while maintaining uniform thickness in the central optic zone. This localized thickness differentiation provides rotational stability without significantly affecting overall lens shape and comfort.
Data Source
AI summary
Toric contact lenses employing a stabilization mechanism to minimize the effect of asymmetric eyelid bias in settled orientation of the toric contact lens, and related methods of design. The toric contact lens includes stabilization zones that are each disposed horizontal sides of the lens periphery of the contact lens between its central optic zone and the lens edge. To minimize the effect of asymmetric bias of an eyelid of a patient wearer on the alignment of the toric contact lens to the principal meridians of the eye, the portion of the contour lines in the stabilization zones that are configured to intersect with an upper eyelid margin in wear are oriented to a target upper eyelid margin shape of a target upper eyelid of an average patient wearer. In this manner, the stabilization zone of the toric contact lens is more desensitized to any asymmetric shape of the wearer's eyelid.