Toric Intraocular Lens Variable Thickness Optical Zone
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Solution Overview
Problem
Conventional intraocular lenses with rotational symmetric surfaces are not suitable for correcting astigmatic refractive errors, and toric lenses with constant edge thickness result in a small effective optical zone, leading to adverse side effects from higher order astigmatic aberrations.
Innovation Solution
Designing an intraocular lens with a toric optic featuring a most curved and a flattest meridian, where the effective optical zone is greater or equal in both meridians, allowing adjustable optical diameters independent of toricity, and incorporating a transition zone between the toric optic and haptics to prevent boundary effects, along with a sharply defined edge on the posterior side to prevent posterior capsular opacification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a toric lens with constant edge thickness is used to correct astigmatism, then the astigmatic refractive error is corrected, but the effective optical zone becomes very elliptic and too small, causing higher order astigmatic aberrations
Solution Approach 1:
The patent applies different thickness characteristics to different regions of the lens. The central optical zone has variable thickness to maintain a large effective optical area, while the peripheral region transitions to constant thickness to provide structural stability and haptic integration. This local differentiation allows the lens to correct astigmatism effectively while maintaining a large optical zone.
Solution Approach 2:
The lens is segmented into distinct zones: a central optical zone with variable thickness for optimal optical performance and a peripheral zone with constant thickness for structural support. This segmentation allows each region to fulfill its specific function without compromising the other, resolving the contradiction between optical zone size and astigmatic correction.
2Ease of manufacture
If the edge thickness of the toric lens is kept constant to simplify manufacturing, then production is easier, but the optically effective surface becomes very elliptic reducing the optical zone
Solution Approach 1:
The manufacturing process is simplified by dividing the lens into zones with different thickness characteristics. The peripheral constant thickness region is easier to manufacture and provides structural stability, while the central variable thickness region optimizes the optical zone. This local quality approach maintains manufacturing ease while improving optical performance.
3Area of stationary object
If toric surfaces are formed on both sides of the lens to retain larger effective optical zone, then the optical zone is larger, but production costs increase and alignment errors may occur
Solution Approach 1:
The patent extracts the toric surface correction primarily to the front surface of the lens, rather than distributing it equally on both surfaces. This simplification reduces manufacturing complexity and alignment requirements while maintaining sufficient optical zone size. The rear surface has minimal or no toricity, reducing the risk of alignment errors during production.
4Device complexity
If the smallest diameter of the optical zone is defined by the degree of toricity, then the lens structure is simplified, but the optical zone diameter cannot be adjusted to a desired diameter
Solution Approach 1:
The patent introduces dynamic adjustability to the optical zone diameter through the variable thickness design in the central region. This allows the effective optical zone diameter to be independently adjusted without being constrained by the toricity degree. The lens structure remains relatively simple while gaining the versatility to adapt to different optical zone requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables adjustable and nearly circular optical zones, reducing adverse side effects from astigmatic aberrations and preventing posterior capsular opacification, while maintaining a larger effective optical area.
Implementation Method 1
the incident light rays are focused upon a point on the retina
Data Source
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AI summary
The invention relates to an intraocular lens (IOL) with a toric optic for the correction of astigmatism, with on one side of a lens a most curved meridian with a most curved lens curvature and a flattest meridian with a lens curvature which is flatter than the most curved lens curvature, wherein an effective optical zone in the most curved meridian is larger or essentially equal to the effective optical zone in the flattest meridian.