Multifocal Ophthalmic Lens Diffractive Steps Visual Acuity
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Solution Overview
Problem
Current intraocular lenses (IOLs) do not effectively provide a smooth transition between distance, intermediate, and near vision focal points, leading to gaps in visual acuity and energy distribution.
Innovation Solution
A multifocal ophthalmic lens with a diffractive element comprising a plurality of annular diffractive steps, each defined by a curved slope and peak, and a diffraction efficiency of less than ten percent, which divides incoming optical energy into multiple focal points, with the zero-order diffraction providing distance vision, and the second and third orders providing intermediate and near vision, respectively, while minimizing energy allocation to the first-order diffraction to enhance bridging energy between focal points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional intraocular lenses are used, then the lens structure is simple, but the visual transition between focal points is discontinuous with gaps in visual acuity
Solution Approach 1:
The lens surface is segmented into multiple annular diffractive steps (echelettes) with different heights, where each step corresponds to a specific focal point. This segmentation divides the optical function into discrete zones that collectively provide continuous visual coverage across multiple focal distances.
Solution Approach 2:
The invention transitions from a conventional single-focal lens to a multifocal lens by adding the dimension of diffractive order multiplication. The curved slope profiles create multiple diffractive orders (0th, 1st, 2nd, 3rd) that correspond to different focal points, effectively adding a focal depth dimension to the optical system.
2Reliability
If diffractive elements with standard profiles are used, then manufacturing is easier, but energy distribution across focal points is inefficient with gaps in visual coverage
Solution Approach 1:
The invention optimizes specific parameters of the diffractive steps including the curved slope profiles, step heights, and radial positions to achieve optimal energy distribution. By carefully controlling these parameters, the lens directs appropriate amounts of light energy to each diffractive order, ensuring efficient coverage across all focal points without manufacturing gaps.
3Reliability
If uniform diffraction efficiency is applied to all orders, then the diffractive structure is simpler, but visual acuity gaps occur due to insufficient bridging energy between focal points
Solution Approach 1:
Different regions of the lens (different diffractive orders) are assigned different diffraction efficiencies tailored to their specific functional requirements. The curved slope profiles create non-uniform diffraction efficiency distribution where certain orders receive enhanced energy allocation to serve as bridging zones between primary focal points, optimizing visual continuity across the full range of vision.
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 solution enhances visual acuity by distributing energy efficiently across focal points, providing a smooth transition between distance and intermediate vision, and maintaining strong focus in all vision ranges without noticeable gaps.
Implementation Method 1
a diffractive element, the diffractive element producing constructive interference in at least four consecutive diffractive orders
Implementation Method 2
producing constructive interference in at least four consecutive diffractive orders, wherein the constructive interference produces a near focus, a distance focus, and an intermediate focus
Data Source
AI summary
Provided in this document are examples of a multifocal ophthalmic lens. The lens includes a base lens having a base curvature corresponding to a base power; and a diffractive structure comprising a plurality of annular echelettes formed on a first surface of the base lens. The diffractive structure is configured to produce a zero-order diffraction corresponding to a distance vision focal point determined by the base power, the diffraction efficiency of the zero-order diffraction between 45% and 55%; a first-order diffraction having a diffraction efficiency between 5% and 10%; a second-order diffraction corresponding to an intermediate vision focal point, the diffraction efficiency between 15% and 20%; and a third-order diffraction corresponding to a near vision focal point, the diffraction efficiency between 15% and 25%. The diffractive structure includes a plurality of annular diffractive steps, each defined by a profile having a curved slope and a peak.