Non-prolate Aspheric Intraocular Lens Misalignment Compensation
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Solution Overview
Problem
Current intraocular lenses (IOLs) face challenges in maintaining imaging quality due to pupil dilation and lens misalignment, as they are designed primarily to address spherical aberrations, which are insufficient in compensating for the effects of pupil size changes and tilt or decentration, leading to reduced image quality, especially at larger pupils.
Innovation Solution
The design incorporates a non-prolate aspheric surface with regions of different signs of longitudinal ray aberrations, which compensates for the effects of pupil dilation and lens misalignment by creating a compensatory effect on the spot diagram, ensuring improved image quality by distributing rays appropriately across the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a spherical IOL design is used, then manufacturing is simple, but imaging quality deteriorates with pupil dilation and lens misalignment
Solution Approach 1:
The patent applies aspheric curvature to the IOL surface, transitioning from a spherical design to an aspheric design where the radius of curvature varies across the surface. This allows the lens to maintain superior imaging quality across different pupil sizes and misalignment conditions while remaining manufacturable using conventional techniques.
Solution Approach 2:
The patent implements different asphericities in different zones of the lens surface. The central zone has one asphericity to optimize photopic vision, while the peripheral zone has a different asphericity to manage mesopic vision and reduce sensitivity to misalignment. This local differentiation resolves the contradiction by optimizing performance across varying conditions.
2Reliability
If a prolate aspheric surface is used to correct spherical aberration, then spherical aberration is reduced, but sensitivity to lens misalignment increases
Solution Approach 1:
The patent divides the lens surface into multiple zones with different asphericities. The central zone corrects spherical aberration for photopic vision, while the peripheral zone is designed with different asphericity to reduce the impact of misalignment. This local differentiation allows the lens to maintain robustness against misalignment while still correcting spherical aberration.
Solution Approach 2:
The patent segments the aspheric surface into distinct zones (central and peripheral) with different optical properties. This segmentation allows each zone to address specific optical issues - the central zone for spherical aberration correction and the peripheral zone for misalignment tolerance - thereby resolving the contradiction between aberration correction and misalignment sensitivity.
3Reliability
If aspherization is incorporated into the base profile over diffractive echelettes, then image contrast improves for pupils above 4 mm, but the design becomes more complex
Solution Approach 1:
The patent applies aspherization specifically to the peripheral zone of the lens rather than the entire surface. This localized approach improves image contrast for dilated pupils while minimizing the increase in manufacturing complexity by limiting the aspheric modification to only where it is most needed.
Data Source
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AI summary
An intraocular lens for implantation into a human eye is described. The lens has at least one aspheric surface configured, with non-prolate profile to maintain lens optical advantage as compared with equivalent power spherical lens within realistic clinical condition of lens tilt and decentration.