Extended-Depth-of-Focus Intraocular Lens With Photopic Zoning
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Solution Overview
Problem
Existing intraocular lenses (IOLs) providing extended depth of focus (EDOF) suffer from individual-to-individual variation in performance due to differences in pupillary size, corneal aberrations, and sensitivity to scattered light, leading to varying visual quality and increased dysphotopsia.
Innovation Solution
Designing IOLs with EDOF features located within a radial position corresponding to the pupil of the user's eye for photopic vision conditions, limiting these features to an inner portion of the photopic pupil to reduce individual variations and minimize dysphotopsia, by maintaining base power over at least 30% of the radial distance of the pupil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If EDOF features are extended to larger radial positions to increase depth of focus, then extended depth of focus is improved, but individual-to-individual variation increases and dysphotopsia increases
Solution Approach 1:
The patent applies local quality by creating distinct radial zones with different optical properties: an inner photopic zone (0-1.5mm) with base power for distance vision and an outer scotopic zone (1.5-3.0mm) with EDOF features. This zonal differentiation allows the lens to provide different visual functions in different regions, achieving extended depth of focus while limiting aberrations in the photopic zone to reduce individual variation and dysphotopsia.
2Adaptability or versatility
If EDOF features are extended to larger radial positions to increase depth of focus, then extended depth of focus is improved, but light scattering increases
Solution Approach 1:
The patent segments the lens optic into two functional zones: a photopic vision zone with radius of 1.5mm containing base power for distance vision, and a scotopic vision zone extending to 3.0mm containing EDOF features. This segmentation isolates the EDOF features to the outer zone, allowing them to extend depth of focus without causing excessive light scattering in the inner photopic zone where vision quality is most critical.
3Measurement precision
If base power is maintained over larger radial distance to improve distance vision, then distance vision quality is improved, but extended depth of focus capability is reduced
Solution Approach 1:
The patent resolves this contradiction by transitioning from a one-dimensional trade-off to a two-dimensional zonal distribution. The base power is maintained specifically in the photopic zone (inner 1.5mm) for optimal distance vision, while EDOF features are implemented in the scotopic zone (outer 1.5-3.0mm) to provide extended depth of focus. This spatial dimensionality allows both functions to coexist without compromising either.
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
Reduces individual-to-individual variation in EDOF IOL performance and wearer satisfaction by limiting aberrations and light scattering, thereby decreasing the likelihood of dysphotopsia.
Implementation Method 1
Refractive multifocal IOLs have an optic that is divided into multiple refractive power regions with light from a particular region being directed, using refractive power, to only one corresponding lens focus
Implementation Method 2
diffractive multifocal lenses use a diffractive element comprising radial zones to direct light to the foci
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
An intraocular lens providing an extended depth of focus, having a power profile that, in a first region, is increasing to an outer edge to achieve a lens power greater than base power and, in a second region is decreasing to achieve a minimum lens power that is less than the base power, and then increasing to achieve the base power, the second region maintaining the base power over at least 30% of the radial distance corresponding to a pupil of an eye for photopic vision conditions. An IOL using refractive features within a 1.4 mm radial distance of the optical axis to generate an MTF having a first peak with an absolute maximum MTF value of at least 0.35 and a region continuous with the first peak maintaining an MTF value of at least 0.15 to achieve a depth of focus of at least about 1.25 diopters.