Multifocal Contact Lens Pupil Apodization Design
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Solution Overview
Problem
Conventional multifocal contact lenses fail to account for individual pupil size variations and the Stiles-Crawford effect, leading to inefficient light distribution and suboptimal visual correction across different viewing conditions.
Innovation Solution
Designing multifocal lenses that scale based on both pupil size and the Stiles-Crawford effect, using a method that adjusts optical zones to optimize light distribution by considering the varying pupil sizes and light sensitivity across the pupil, with equations to calculate effective pupil diameters and zone ratios for improved visual acuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multifocal contact lenses use fixed optical zones, then manufacturing is simple, but visual correction efficiency deteriorates due to pupil size variations and Stiles-Crawford effect
Solution Approach 1:
The patent applies dynamics by making the optical zone boundaries variable rather than fixed. The lens design incorporates multiple concentric zones with different optical powers, where the effective zone boundaries dynamically adapt to the wearer's pupil size through the apodization profile. This allows the lens to optimize light distribution across different viewing conditions while maintaining a single manufacturable structure.
Solution Approach 2:
The patent changes the parameter of optical power distribution across the lens surface using an apodization profile. Instead of abrupt zone boundaries, the optical power gradually transitions between zones according to a mathematical function that accounts for pupil size and the Stiles-Crawford effect. This continuous parameter change optimizes visual correction efficiency across varying luminance conditions.
2Reliability
If multifocal lenses account for pupil size variations, then light distribution improves, but the Stiles-Crawford effect is not addressed leading to suboptimal visual results
Solution Approach 1:
The patent transforms the optical power distribution parameter using an apodization function that incorporates both pupil size and Stiles-Crawford effect parameters. The optical power P(r) at radial distance r is modified by an apodization factor A(r) that gradually reduces power near the pupil edges, accounting for the reduced sensitivity of cones to oblique rays. This creates a smooth transition that optimizes light utilization across the entire pupillary aperture.
3Measurement precision
If optical zones are scaled to match pupil size, then distance correction is optimized, but near vision correction becomes inefficient under high luminance
Solution Approach 1:
The patent segments the lens into multiple concentric optical zones with different power distributions. The central zone provides distance correction while annular zones provide near vision correction. The apodization profile creates smooth transitions between these zones, allowing both distance and near vision to be optimized simultaneously by distributing light appropriately across different zones based on pupil size and viewing conditions.
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 provides enhanced visual correction by optimizing light distribution and zone ratios, improving visual acuity across various lighting conditions and pupil sizes, particularly addressing the inefficiencies in conventional multifocal lenses.
Implementation Method 1
the cones of the eye are more sensitive to light rays that strike perpendicular to the cones' surface than other rays. Thus, the intensity of the response to light peaks at or near the center of the pupillary aperture and decreases towards the edges, a phenomenon known as the Stiles-Crawford effect of the first kind ('Stiles Crawford Effect' or 'SCE')
Data Source
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AI summary
The invention provides a contact lens that corrects for the wearer's refractive prescription by taking into account both pupil size and the Stiles Crawford effects of the first order.