Aspheric Multifocal Intraocular Lens for Stable Intermediate Vision
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Solution Overview
Problem
Current multifocal intraocular lenses face issues with image quality, particularly in intermediate focal regions, and are limited by pupil size and lighting conditions, leading to blurred images and color effects like halos in polychromatic light.
Innovation Solution
A refractive multifocal intraocular lens with aspheric geometry on both surfaces, featuring a central region of intermediate optical strength surrounded by rings of varying strength, providing smooth transitions and optimized optical quality for a wide range of distances and pupil sizes, combining the optics of the cornea and intraocular lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multifocal intraocular lenses are used to provide multiple focuses, then near and far vision are improved, but image quality in intermediate focal regions deteriorates with blurred images
Solution Approach 1:
The lens applies local quality by creating distinct zones with different optical powers: a central zone for distance vision, an intermediate annular zone for intermediate distances, and a peripheral annular zone for near vision. Each zone is optimized for its specific focal range, allowing the lens to provide multiple focuses while maintaining sharp images in each region rather than compromising intermediate vision.
Solution Approach 2:
The lens segments the optic region into multiple functional zones with different refractive powers. The optic region is divided into a central zone, an intermediate annular zone, and a peripheral annular zone, each contributing to different focal points. This segmentation allows simultaneous provision of multiple focuses while maintaining image quality through proper zonal design.
2Adaptability or versatility
If diffractive lenses are used to create multiple focuses, then near and far vision are achieved, but color effects like halos appear in polychromatic light
Solution Approach 1:
The invention replaces the diffractive optical mechanism with a refractive mechanism. Instead of using diffraction gratings or microstructures that split light into multiple wavelengths causing halos, the lens uses refractive index differences and curved surfaces to bend light into multiple focal points. This substitution of the optical mechanism eliminates the wavelength-dependent diffraction effects that cause color separation and halo artifacts.
Solution Approach 2:
The lens changes the optical parameter from diffraction-based focusing to refraction-based focusing. By utilizing the refractive properties of the lens material and varying the curvature across different zones, the lens achieves multifocality through refraction rather than diffraction, thereby avoiding the color effects and halos associated with diffractive designs.
3Measurement precision
If monofocal intraocular lenses are used to correct distance vision, then optical quality for far distances is optimized, but near vision capability is lost
Solution Approach 1:
The lens applies local quality by creating distinct zones with different optical powers: a central zone for distance vision, an intermediate annular zone for intermediate distances, and a peripheral annular zone for near vision. Each zone is optimized for its specific focal range, allowing the lens to provide multiple focuses while maintaining sharp images in each region rather than compromising intermediate vision.
Solution Approach 2:
The lens achieves multi-functionality by incorporating multiple focal zones within a single optical element. The central zone provides distance correction, the intermediate annular zone provides intermediate distance correction, and the peripheral annular zone provides near vision correction. This allows the single lens to perform multiple functions that would otherwise require separate corrective devices.
4Adaptability or versatility
If refractive multifocal lenses with concentric sections are used, then multiple focuses are achieved, but performance is limited by variable pupil size and lighting conditions
Solution Approach 1:
The lens incorporates dynamic adaptability by designing zones that automatically become more or less dominant based on pupil size and lighting conditions. The intermediate annular zone is positioned and sized to provide stable intermediate vision across a range of pupil diameters, while the central and peripheral zones provide distance and near vision respectively. This dynamic zonal design ensures reliable performance whether the pupil is constricted in bright light or dilated in dim light.
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 lens offers stable, high-contrast vision across various distances with optimized optical quality, independent of pupil size and lighting conditions, significantly improving upon previous refractive and diffractive designs by maintaining performance in intermediate vision and reducing variations with different pupillary diameters.
Implementation Method 1
a map of local optical strength inside said optic region, resulting from the combined optical refraction of said two aspheric optical surfaces and a model cornea
Data Source
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Figure 3~4
AI summary
The present invention describes a refractive multifocal intraocular lens with aspheric geometry on both surfaces in such a way that the map of local optical strength of the lens, combined with the cornea, has a central region of intermediate optical strength surrounded by a ring of maximum optica! strength, with a smooth transition between the two, after which it a!ternates smoothly between rings of varying strengths.