Phase-Shifted Diffractive Multifocal IOL Design
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Solution Overview
Problem
Current multifocal intraocular lenses often fail to provide clear vision across a range of object distances, particularly for intermediate vision, and are inadequate in compensating for the lost optical power following the removal of a natural lens, especially in varying lighting conditions.
Innovation Solution
The development of an improved diffractive multifocal design for ocular implants that incorporates both diffractive and refractive regions, with a central diffractive portion and a surrounding refractive area, allowing for phase-shifting to redistribute energy between near, intermediate, and distant focal points, enhancing vision across different lighting conditions and pupil sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a diffractive IOL with two focal lengths (far and near) is used, then the patient gains versatile focusing properties, but intermediate vision quality deteriorates
Solution Approach 1:
The IOL is divided into multiple distinct regions: a central diffractive region for near and intermediate vision, an intermediate refractive region, and a peripheral refractive region for distance vision. This segmentation allows each region to contribute to specific focal points, thereby improving overall visual performance across all distances including intermediate vision.
Solution Approach 2:
Different regions of the IOL are assigned different optical properties: the central region uses diffractive optics with specific phase shifts to create near and intermediate foci, while the peripheral region uses refractive optics for distance vision. This local differentiation of optical characteristics enables optimized vision at each distance without compromising intermediate vision quality.
2Adaptability or versatility
If diffractive structures are used to provide multiple focal lengths, then near and far focus are achieved, but energy distribution becomes unbalanced across different focal points
Solution Approach 1:
The patent applies specific phase shift values (e.g., 1/2 wave, 1/4 wave, or other fractional wave shifts) to the diffractive regions to control the distribution of light energy among different focal points. By adjusting these phase shift parameters, the design optimizes energy allocation to ensure adequate illumination at near, intermediate, and distance foci simultaneously.
Solution Approach 2:
The IOL design incorporates dynamic energy distribution that adapts to viewing conditions. The diffractive and refractive regions work together to dynamically allocate optical energy based on the object distance, ensuring that sufficient energy reaches the appropriate focal point whether the patient is viewing near, intermediate, or distance objects.
3Reliability
If a multifocal IOL is implanted to replace the natural lens, then cataract is treated and some vision is restored, but vision across a full range of object distances remains inadequate
Solution Approach 1:
The IOL is designed as a multi-functional optical device that simultaneously provides near, intermediate, and distance vision capabilities in a single implant. The combination of diffractive and refractive regions creates multiple focal points, enabling the lens to perform multiple visual functions that would otherwise require separate optical elements or the natural accommodative mechanism.
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 provides improved distance and near vision at smaller pupils and enhanced intermediate vision at larger pupils, offering increased independence from glasses and better visual performance in both photopic and mesopic conditions, with reduced visual disturbances.
Implementation Method 1
Diffractive lenses use nearly periodic microscopic structures on the lens to diffract light into several directions simultaneously. This is similar to a diffraction grating and the multiple diffraction orders focus the light into various images corresponding to different focal lengths of the lens.
Implementation Method 2
The diffractive multifocal IOL includes both a diffractive region and a refractive region, the diffractive multifocal IOL operable to phase shift optical energy such that constructive interference occurs within the diffractive region and the refractive region.
Implementation Method 3
Various multifocal ophthalmic lens designs generally fall into one of two categories, refractive lenses and diffractive lenses.
Data Source
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AI summary
A diffractive multifocal design for ocular implant is provided. This ocular implant includes a diffractive multifocal intraocular lens (IOL) and a number of haptics. The diffractive multifocal IOL passes optical energy to distance, intermediate and near foci. The haptics mechanically couple to the diffractive multifocal IOL in order to position and secure the diffractive multifocal IOL within the eye. The diffractive multifocal IOL may include both a diffractive region and a refractive region, the diffractive multifocal IOL operable to phase shift optical energy such that constructive interference occurs within the diffractive region and the refractive region.