Multi-axis Toric Lens Design for Astigmatism
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Solution Overview
Problem
Toric contact lenses face challenges with rotational stabilization, particularly for plus powered lenses, and require a large number of cylindrical axis placements to fit astigmatic patients, leading to sensitivity issues and increased stock keeping units (SKUs).
Innovation Solution
The design incorporates a multifocus axis component with varying lens design parameters in the optical zone, utilizing concentric annular rings or continuously varying lens parameters to reduce reliance on rotational stabilization and increase cylinder axis increments, thereby minimizing toric axis misalignment sensitivity and reducing the number of SKUs needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional stabilization techniques (prism stabilization, thickening inferior periphery, etc.) are used to maintain toric contact lens orientation, then rotational stability is improved, but the design complexity and reliance on mechanical characteristics increase
Solution Approach 1:
The optical zone is segmented into multiple sub-zones with different cylindrical axes. This segmentation allows the lens to provide astigmatic correction for multiple orientations simultaneously, reducing the need for complex mechanical stabilization mechanisms while maintaining visual acuity across different rotational positions.
Solution Approach 2:
Different sub-zones within the optical zone are assigned different local optical properties (different cylindrical axes). This local differentiation enables the lens to correct astigmatism effectively even when rotated, as each sub-zone addresses specific orientation requirements, thereby reducing dependence on complex stabilization features.
2Adaptability or versatility
If a large number of cylindrical axis placements (SKUs) are provided to fit astigmatic patients, then adaptability is improved, but inventory complexity and cost increase
Solution Approach 1:
A single toric contact lens design incorporates multiple cylindrical axes within different sub-zones, making it universally applicable to patients with various astigmatic orientations. This multi-functional design eliminates the need for multiple specialized lenses (SKUs), as one lens can effectively correct astigmatism across different axis placements.
Solution Approach 2:
The patent combines multiple cylindrical axis corrections into a single lens by creating overlapping or adjacent sub-zones with different axes. This merging of functions into one product reduces the total number of SKUs required, as patients no longer need separate lenses for different axis placements.
3Reliability
If toric contact lenses are designed with mechanical stabilization features, then orientation maintenance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces mechanical stabilization systems (such as prism ballast or thickened peripheries) with an optical solution consisting of multiple sub-zones with different cylindrical axes. This substitution eliminates complex mechanical manufacturing steps while maintaining reliable orientation maintenance through optical design alone.
Data Source
AI summary
A toric contact lens utilizes concentric annual rings, a continually varying lens design as a function of distance from the lens center or any other function to create a range of cylinder axis zones on a single lens.