Double-Sided Aspheric Diffractive Multifocal Lens for Aberration Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing intraocular lenses (IOLs) face challenges in providing simultaneous near, intermediate, and distance focus while addressing spherical and astigmatic aberrations, which can degrade vision contrast and acuity, especially in patients with presbyopia and cataracts.
Innovation Solution
A double-sided aspheric diffractive multifocal lens design featuring a first aspheric surface and a second aspheric surface with concentric annular zones, each with a periodically structured curve, producing near, intermediate, and distance focuses, and incorporating a toric component to correct astigmatism, thereby enhancing visual acuity and reducing aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a multifocal IOL with diffractive structures is used to provide near and distance focus, then visual acuity at multiple focal distances is improved, but spherical and astigmatic aberrations are introduced that degrade vision contrast
Solution Approach 1:
The lens is divided into multiple functional zones: a central zone for distance focus and concentric annular zones for near and intermediate focus. This segmentation allows different regions to serve different optical purposes, providing multifocality while managing aberrations through zonal control
Solution Approach 2:
Different zones of the lens have different optical properties tailored to specific functions. The central zone has optimized curvature for distance vision, while the annular zones have specific diffractive structures for near and intermediate focus. This local optimization reduces overall spherical and astigmatic aberrations while maintaining multifocal capability
2Ease of manufacture
If conventional spherical lens surfaces are used, then manufacturing is simpler, but spherical aberrations degrade vision contrast especially for large pupil sizes
Solution Approach 1:
The lens employs aspheric surfaces with optimized curvature profiles instead of conventional spherical surfaces. The aspheric design, characterized by varying curvature across the lens surface, corrects spherical aberrations by ensuring that light rays at different distances from the optical axis focus at the same point, thereby improving vision contrast without significantly complicating the manufacturing process
3Reliability
If a single focal point IOL is used to replace the natural lens, then cataract is treated and optical power is restored, but presbyopia cannot be corrected and multiple eyeglasses are needed
Solution Approach 1:
The IOL is designed to perform multiple functions simultaneously: it corrects cataract by replacing the opaque natural lens, provides distance focus through the central zone, and delivers near and intermediate focus through the diffractive annular zones. This multifunctional design eliminates the need for separate corrective eyeglasses for different viewing distances, addressing both cataract and presbyopia with a single implant
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 lens design significantly improves visual acuity and contrast by eliminating spherical and astigmatic aberrations, providing enhanced vision across multiple focal distances, and is more readily fabricable compared to existing multifocal IOLs.
Implementation Method 1
a second aspheric surface including a central zone and a plurality of diffractive elements comprising concentric annular zones extending in a radial direction, each concentric annular zone having a periodically structured curve comprising two smooth turning points between two sharp turning points, thereby producing a near focus (f2), an intermediate focus (f1), and a distance focus (f0)
Implementation Method 2
The lens design significantly improves visual acuity and contrast by eliminating spherical and astigmatic aberrations
Data Source
AI summary
A double-sided aspheric diffractive multifocal lens and methods of manufacturing and design of such lenses in the field of ophthalmology. The lens can include an optic comprising an aspheric anterior surface and an aspheric posterior surface. On one of the two surfaces a plurality of concentric diffractive multifocal zones can be designed. The other surface can include a toric component. The double-sided aspheric surface design results in improvement of the modulation transfer function (MTF) of the lens-eye combination by aberration reduction and vision contrast enhancement as compared to one-sided aspheric lens. The surface having a plurality of concentric diffractive multifocal zones produces a near focus, an intermediate focus, and a distance focus.