Progressive Lens Astigmatism Axis Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Progressive multifocal ophthalmic lenses often suffer from astigmatism defects, particularly in the intermediate vision zone, where the axis of astigmatism is not optimally controlled, leading to suboptimal visual experience for presbyopic wearers.
Innovation Solution
A method for determining a progressive multifocal ophthalmic lens that optimizes the axis values of resulting astigmatism in addition to its modulus, using specific control zones and ellipses to align the average orientation of astigmatism axes with the vertical, thereby improving the lens's performance and field of vision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If progressive multifocal lenses are designed with power progression zones, then presbyopic wearers gain improved near and intermediate vision, but astigmatism defects appear in the intermediate vision zone
Solution Approach 1:
The patent applies local quality by differentiating the optimization criteria for different zones of the lens. The intermediate vision zone is assigned specific targets for astigmatism modulus and axis orientation, while other zones have different optimization priorities. This allows each zone to have tailored optical properties that address its specific functional requirements without compromising overall lens performance.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying the astigmatism modulus and axis orientation parameters across different zones of the lens surface. Through iterative optimization, the lens design adjusts these parameters to minimize astigmatism defects in the intermediate zone while maintaining appropriate power progression for presbyopic correction.
2Reliability
If the lens is optimized for power progression, then presbyopic vision needs are met, but the axis orientation of astigmatism is not optimally controlled
Solution Approach 1:
The patent segments the lens into distinct optimization zones: a distance vision zone, an intermediate vision zone, and a near vision zone. Each zone has specific optimization targets, with the intermediate zone receiving special attention for astigmatism axis control. This segmentation allows independent optimization of each zone's optical characteristics without interfering with the overall power progression design.
Solution Approach 2:
The patent employs dynamic optimization through iterative ray tracing and parameter adjustment. The lens design process dynamically adjusts surface parameters to simultaneously satisfy multiple constraints including power progression, astigmatism modulus control, and axis orientation alignment. This dynamic approach enables the lens to meet both power correction accuracy and astigmatism axis control requirements.
3Reliability
If astigmatism correction is added to the lens prescription, then astigmatic defects are compensated, but lens complexity increases
Solution Approach 1:
The patent merges the astigmatism correction function with the progressive power progression design into a single integrated lens surface. Rather than adding separate corrective elements, the astigmatism compensation is incorporated into the overall lens curvature and power distribution. This merging approach provides astigmatism correction while maintaining the progressive multifocal design without significantly increasing manufacturing complexity.
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
The method involves choosing a starting lens having a fitting cross marking a primary viewing direction under wearing conditions and an umbilical progression meridian. The meridian is provided with a power addition greater than or equal to two diopters between far and near vision reference points. A current lens used as target is optimized under wearing conditions. A progression length is defined as the angle of lowered viewing from the fitting cross to a point of the meridian at which a wearer`s optical power reaches 85 percentages of a prescription. Independent claims are also included for the following: (1) a progressive multifocal ophthalmic lens with a complex surface (2) a visual device comprising a progressive multifocal ophthalmic lens (3) a method for correcting a vision of a presbyopic subject.