Zonal Diffractive Multifocal Intraocular Lens Design
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Solution Overview
Problem
Current multifocal intraocular lenses (IOLs) may experience clarity issues in far vision, especially in photopic conditions, indicating a need for enhanced refractive and diffractive optical focusing powers.
Innovation Solution
The development of a multifocal IOL with a central refractive region and a diffractive region on at least one surface, providing equal refractive and diffractive focusing powers for near and far vision, with the option of an outer refractive region contributing to focusing powers, and varying step heights in the diffractive zones to optimize light energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a diffractive structure is added to provide near-focus power, then accommodation is improved, but far vision clarity deteriorates
Solution Approach 1:
The lens is divided into distinct functional zones: a central refractive region for far vision and an outer diffractive region for near vision. This segmentation allows each zone to optimize its specific function without interfering with the other, resolving the contradiction between near-focus accommodation and far vision clarity
Solution Approach 2:
Different regions of the lens are assigned different optical properties - the central region provides refractive far-focus power while the outer annular region provides diffractive near-focus power. This local differentiation enables simultaneous optimization of both far and near vision capabilities
2Ease of manufacture
If diffractive zones with uniform step heights are used, then manufacturing is simplified, but light energy distribution and visual acuity are suboptimal
Solution Approach 1:
The step heights in the diffractive zones are varied according to a specific profile (increasing from inner to outer regions) rather than being uniform. This parameter change optimizes the distribution of light energy between near and far foci, improving visual acuity while maintaining reasonable manufacturability
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 IOL effectively provides clear far and near vision by optimizing light energy distribution across different pupil sizes, ensuring improved visual acuity and accommodation.
Implementation Method 1
a central refractive region for providing one refractive focusing power
Implementation Method 2
A diffractive region is disposed on at least one of the lens surfaces for providing a near and far diffractive focusing power
Data Source
Figure 1A~1B
Figure 2~3
Figure 4A~5A
AI summary
The present invention generally provides multifocal ophthalmic lenses, e.g., multifocal intraocular lenses (10), that employ a central refractive region (18) for providing a refractive focusing power and a diffractive region (20) for providing two diffractive focusing powers. In many cases, 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. As such, in many cases, the focusing properties of the lenses are dominated by the far-focus ability, especially for small pupil sizes.