Multifocal Intraocular Lens Central Zone Design
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Solution Overview
Problem
Existing multifocal intraocular lenses face challenges in enhancing image contrast for both far-focus and near-focus powers due to limitations in diffractive structure design, which affects the division of energy between these focuses and is influenced by imaging aberrations.
Innovation Solution
The design incorporates a central refractive region surrounded by a diffractive region, with adjustable step heights and curvatures to optimize image contrast, allowing for equal refractive and diffractive far focusing powers, and additional outer refractive regions to provide distinct focusing powers, thereby directing more energy to the distance focus while maintaining near-focus capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the step heights of the diffractive structure are increased to enhance near-focus power, then near-focus energy is improved, but far-focus image contrast deteriorates
Solution Approach 1:
The lens is divided into distinct functional zones: a central refractive zone for far-focus and an outer diffractive zone for near-focus. This segmentation allows each zone to independently optimize its function without interfering with the other, resolving the energy distribution conflict between near and far focuses
Solution Approach 2:
Different regions of the lens are assigned different optical properties: the central zone has refractive characteristics optimized for far-focus, while the outer zone has diffractive characteristics optimized for near-focus. This local differentiation enables simultaneous optimization of both focusing powers
2Use of energy by moving object
If energy is increased to one focus, then that focus power is improved, but energy to the other focus is reduced, worsening image contrast
Solution Approach 1:
The lens aperture is segmented into a central refractive zone and an outer diffractive zone, allowing independent energy distribution control. The central zone directs energy to far-focus while the outer zone directs energy to near-focus, eliminating the zero-sum energy trade-off
Solution Approach 2:
The solution moves from a single-zone design to a multi-zone radial configuration, adding a spatial dimension (radius) to energy distribution. This allows different radial zones to contribute to different focal points simultaneously
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 configuration enhances image contrast and adjusts energy distribution to optimize both far and near focusing powers, improving the overall optical performance of multifocal intraocular lenses by directing more light to the distance focus and maintaining acceptable near-focus power.
Implementation Method 1
A diffractive region is disposed on at least one of the lens surfaces for providing a near and far diffractive focusing power
Implementation Method 2
The optic includes a central refractive region for providing a refractive focusing power
Data Source
Figure 1~3
Figure 2B~2C
Figure 4
AI summary
The present invention generally provides multifocal ophthalmic lenses, e.g., multifocal intraocular lenses, that employ a central refractive region for providing a refractive focusing power and a diffractive region for providing diffractive focusing powers. The refractive focusing power provided by the lens's central region corresponds to a far-focusing power that is substantially equal to one of the diffractive focusing powers while the other diffractive power corresponds to a near-focusing power. The far-focusing power can be enhanced by changes to the phase of the central refractive region and/or changes to the curvature of the central refractive region.