Diffractive IOL Apodization for Near Vision and Glare
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Solution Overview
Problem
Conventional intraocular lenses (IOLs) have limitations in accommodating varying eye geometries and pupil sizes, leading to suboptimal performance for patients with non-standard physical characteristics, particularly in providing adequate near vision and correcting issues like presbyopia.
Innovation Solution
The development of an ophthalmic lens with a diffraction grating on its anterior or posterior surface, divided into zones with specific echelette step heights and radii of curvature, allowing for multiple focal lengths and adaptability by repeating characteristics of inner zones in outer regions to enhance near vision and accommodate different pupil sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional diffractive IOLs use standard apodization patterns with decreasing step heights from center to edge, then glare and halos are reduced, but near vision performance deteriorates for patients with larger pupil sizes
Solution Approach 1:
The patent applies dynamic apodization by making the step height of echelettes variable not only radially but also azimuthally. The apodization pattern dynamically adjusts based on the local functional requirement: central zones have higher step heights for near vision, while peripheral zones have lower step heights for reducing glare. This dynamic configuration allows the lens to adapt to different pupil sizes and viewing conditions, resolving the contradiction between near vision performance and glare reduction.
Solution Approach 2:
The patent implements local quality by assigning different apodization characteristics to different regions of the lens. Instead of a uniform radial gradient, the step heights are optimized locally: the central region has higher step heights to prioritize near vision, while the peripheral region has lower step heights to minimize optical artifacts. This localized optimization allows each zone to serve its specific functional purpose, simultaneously improving near vision and reducing glare.
2Ease of manufacture
If the lens is designed for a specific focal length, then manufacturing is simplified, but adaptability to varying eye geometries and pupil sizes deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the lens into multiple functional zones with distinct echelette configurations. Each zone is designed with specific step heights and radial positions to serve different focal requirements. This segmentation allows the lens to provide multiple focal lengths and accommodate varying eye geometries while maintaining a relatively simple manufacturing process, as each zone can be fabricated using standardized techniques.
Solution Approach 2:
The patent implements universality by designing the lens to perform multiple functions simultaneously: it provides near vision, intermediate vision, and far vision focal lengths; it accommodates different pupil sizes; and it reduces optical artifacts. The multi-functional design achieves this through the strategic arrangement of echelettes with varying step heights across different zones, allowing a single lens to serve diverse patient requirements without requiring custom designs for each application.
3Ease of manufacture
If step heights are uniformly distributed across all zones, then manufacturing is easier, but optical artifacts increase and near vision performance decreases
Solution Approach 1:
The patent applies local quality by varying the step heights of echelettes according to the specific functional requirements of different lens zones. The central zones have higher step heights to optimize near vision, while peripheral zones have progressively lower step heights to minimize optical artifacts such as glare and halos. This localized variation in step height configuration allows the lens to achieve optimal optical performance across different regions while maintaining compatibility with existing manufacturing capabilities.
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
This design improves near vision for individuals with larger pupil sizes and accommodates variations in eye structure, providing a more effective multifocal lens system that can correct nearsightedness and presbyopia by dedicating a larger fraction of light energy to near vision.
Implementation Method 1
Diffractive IOLs utilize a diffraction grating formed on a base curve on the surface of the IOL. The echelettes form a diffraction grating having a particular focal length.
Data Source
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AI summary
An ophthalmic device including an ophthalmic lens (110) having anterior and posterior surfaces (114, 112) and at least one diffraction grating (120) is described. The diffraction grating(s) are on the anterior and/or posterior surface(s). The diffraction grating(s) include zones (122, 124, 126). A first zone is at a first distance range from a center of the lens. A second zone is at a second distance range further from the center than the first distance range. A repeat zone is at a third distance range further from the center than the second distance range. The first zone includes echelette(s) (130) having a first step height and a first radius of curvature. The second zone includes echelette(s) (130) having a second step height and a second radius of curvature. The repeat zone includes echelette(s) (130) having at least one of the first step height and the first radius of curvature.