Toric Contact Lens Blend Zone Thickness Adjustment
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Solution Overview
Problem
Toric contact lenses often have varying thicknesses across a series of lenses with different cylindrical corrections, leading to inconsistent fitting characteristics and reduced on-eye comfort and stability.
Innovation Solution
A set of toric contact lenses with a common spherical correction and varying cylindrical corrections, featuring a blend zone with widths adjusted based on cylindrical power to maintain consistent thickness profiles across lenses, along with mold tools configured to produce lenses with specific blend zone widths for consistent fitting characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If lenses are designed with different cylindrical corrections, then optical correction capability is improved, but lens thickness varies considerably leading to inconsistent fitting characteristics
Solution Approach 1:
The patent applies local quality by creating a blend zone with specific thickness characteristics that transitions between the central optical zone and peripheral zone. This blend zone is strategically positioned to compensate for thickness variations caused by different cylindrical corrections, ensuring that the overall lens thickness remains consistent across the series while maintaining the required optical correction capabilities.
Solution Approach 2:
The patent utilizes parameter changes by systematically adjusting the thickness of the blend zone based on the cylindrical correction power. Lenses with higher cylindrical corrections have modified blend zone thicknesses compared to those with lower corrections, which compensates for the additional thickness in the central zone and maintains consistent overall lens thickness and fitting characteristics across the series.
2Adaptability or versatility
If lens thickness is increased to provide higher cylindrical correction, then optical correction is improved, but on-eye comfort and lens stability are reduced
Solution Approach 1:
The patent applies local quality by concentrating the thickness modification in the blend zone rather than uniformly increasing lens thickness. This localized approach provides the necessary cylindrical correction while minimizing the impact on overall lens thickness, thereby maintaining on-eye comfort even for lenses with higher cylindrical corrections.
Solution Approach 2:
The patent segments the lens into three distinct zones: central optical zone, blend zone, and peripheral zone. This segmentation allows independent optimization of each zone's thickness characteristics, enabling the blend zone to compensate for thickness variations and maintain comfort while the central zone provides the required cylindrical correction.
3Adaptability or versatility
If lens thickness is increased to provide higher cylindrical correction, then optical correction is improved, but lens stability is reduced
Solution Approach 1:
The patent utilizes parameter changes by adjusting the blend zone thickness as a function of cylindrical correction power. This systematic parameter adjustment compensates for the thickness variations in the central optical zone, ensuring that lenses with different cylindrical corrections all achieve consistent overall thickness and equivalent stability characteristics on the eye.
Solution Approach 2:
The patent applies local quality by modifying the thickness characteristics specifically in the blend zone to compensate for variations in the central optical zone. This localized thickness adjustment ensures that the overall lens thickness and stability remain consistent across the series, regardless of the cylindrical correction power.
Data Source
AI summary
A set of toric contact lenses, where each lens in the set includes a posterior surface and an anterior surface. For each lens in the set, at least one of the posterior and anterior surfaces includes a toric optical zone. Each lens in the set has a common effective base curve and a common overall diameter, but a different cylindrical correction. Lenses in the set have a peripheral zone and a blend zone disposed between the peripheral zone and the toric optical zone. In lenses of such a set, the width of said blend zone at a common location on at least two of the lenses are selected to be different so that the thicknesses at a common position on the lenses are substantially the same for all lenses in the set.