Reverse Geometry Contact Lens Zoning for Myopia Control Stability
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Solution Overview
Problem
Current contact lenses for myopia control face challenges in effectively managing higher levels of myopia due to issues with suction force strength, lens adhesion, and manufacturing tolerances, leading to potential corneal abrasion and reduced effectiveness.
Innovation Solution
A method and system for designing an aspheric contact lens with specific zone widths and curve profiles that apply both compression and tension forces to reshape the cornea, using a central zone with a base curve profile, a reverse zone with a reverse curve profile, and additional zones to balance forces and prevent lens adhesion, while accommodating manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the suction force strength is increased to control higher levels of myopia, then the myopia control effectiveness is improved, but the lens adhesion to the eyeball surface increases causing potential corneal abrasion
Solution Approach 1:
The contact lens is divided into multiple functional zones: a central treatment zone with a first curve profile that generates compression forces for myopia control, and a peripheral fitting zone with a second curve profile that generates suction forces for stabilization without excessive adhesion. This segmentation allows different regions to perform different functions optimally.
Solution Approach 2:
Different regions of the lens are assigned different curve profiles and mechanical properties. The central zone has a steeper curve profile optimized for compression and myopia control, while the peripheral zone has a flatter curve profile optimized for suction and stabilization. This local differentiation resolves the contradiction between strong suction for control and weak adhesion for comfort.
2Reliability
If the fitting zone width is decreased to increase suction force strength, then the myopia control effectiveness is improved, but the manufacturing tolerance and eyeball tissue reaction accommodation is reduced
Solution Approach 1:
The lens is segmented into a central treatment zone and a peripheral fitting zone with distinct curve profiles. The peripheral fitting zone's specific curve profile is designed to generate appropriate suction forces while maintaining sufficient width to accommodate manufacturing tolerances and individual variations in eyeball tissue elasticity.
Solution Approach 2:
The curve profile parameters (radius of curvature, steepness) are optimized for the peripheral fitting zone to balance suction force generation with adequate zone width. This allows the lens to maintain effective suction while having enough peripheral area to accommodate manufacturing variations and tissue responses.
3Stability of the object's composition
If the fitting zone width is increased to accommodate manufacturing tolerances and tissue reaction, then the lens stability is improved, but the suction force strength is reduced making the lens ineffective for higher diopter values
Solution Approach 1:
The lens is divided into functional zones where the peripheral fitting zone provides stability through appropriate suction forces, while the central treatment zone delivers the compression forces needed for myopia control. This segmentation allows each zone to optimize its function independently.
Solution Approach 2:
The peripheral fitting zone is designed with specific local properties (curve profile, width) that generate stable suction forces adequate for lens positioning, while the central zone has different properties optimized for myopia control. This local quality differentiation resolves the contradiction between stability and control effectiveness.
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 designed lens effectively controls myopia by reshaping the cornea without causing adhesion, reducing the risk of corneal abrasion, and maintaining lens stability, providing long-term myopia control with improved visual acuity.
Implementation Method 1
the base curve profile defining a compression force strength on the cornea when the contact lens is positioned on the eye
Implementation Method 2
the reverse curve profile defining a tension force strength on the cornea when the contact lens is positioned on the eye
Implementation Method 3
a treatment zone (of the contact lens) applies suction to the eyeball in order to reform the eyeball shape and thus decrease the length of the eyeball
Data Source
AI summary
Generating an aspheric contact lens design for facilitating myopia control of a cornea of a patient includes operations of: obtain measurement for degree refractive error of the eye in diopters; obtain measurement of one or more biomechanical properties of the cornea; define a diameter of a central zone of the contact lens based on pupil size; select a base curve profile and width for the central zone based on the refractive error and the one or more biomechanical properties; define a width of a reverse zone adjacent to and encircling the central zone, the width being greater than 0.5 mm; select a reverse curve profile for the reverse zone compatible with the base curve profile; modify the base curve profile adjacent to the reverse zone by applying a selected base eccentricity curve profile for enhancing the tension force strength of the reverse zone; define a width of a relief zone of the contact lens adjacent to and encircling the reverse zone; select a relief curve profile for the relief zone; define a width of an alignment zone of the contact lens adjacent to and encircling the relief zone; select an alignment curve profile for the alignment zone; and define a width of a peripheral zone of the contact lens adjacent to and encircling the alignment zone; select a peripheral curve profile for the peripheral zone; wherein the compression force strength and the tension force strength of the contact lens cooperate to reshape corneal curvature in a mid-peripheral region to address the myopia control when the contact lens is applied to the eye.