Rigid Corneal Contact Lens Peripheral Defocus Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rigid corneal contact lenses fail to address myopia development caused by paracentral hyperopic defocus, leading to peripheral hyperopic defocus issues in users.
Innovation Solution
A rigid contact lens design featuring a front surface with a central spherical zone and a peripheral defocus area where the radius of curvature decreases from the outside, and a back surface with a central spherical zone and a reverse zone where the radius of curvature decreases from the outer side, minimizing peripheral hyperopic defocus by optimizing image projection on the retina.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional spherical mono-focal lens is used, then the lens structure is simple and easy to manufacture, but peripheral hyperopic defocus occurs causing myopia development
Solution Approach 1:
The lens applies different optical properties to different regions: the central optical zone maintains spherical geometry for clear central vision, while the peripheral defocus area implements continuously decreasing radius of curvature to create myopic shift. This local differentiation allows the lens to simultaneously provide clear central vision and reduce peripheral hyperopic defocus, resolving the contradiction between manufacturing simplicity and optical performance.
Solution Approach 2:
The lens is divided into two distinct functional zones: a central optical zone with spherical geometry and a peripheral defocus area with varying curvature. This segmentation allows each zone to perform its specific function independently - the central zone for clear vision and the peripheral zone for myopia control - while together they solve the contradiction between simple manufacturing and effective myopia prevention.
2Ease of manufacture
If the front surface is made completely spherical, then the lens is easy to manufacture, but peripheral image points project behind retina causing myopia
Solution Approach 1:
The front surface implements local quality by maintaining spherical geometry only in the central optical zone while introducing continuously decreasing radius of curvature in the peripheral defocus area. This localized modification of surface geometry enables the lens to maintain manufacturing ease for the central zone while achieving effective myopia control through the peripheral zone's optimized curvature profile.
3Reliability
If peripheral curvature is increased to reduce hyperopic defocus, then myopia control improves, but lens complexity increases
Solution Approach 1:
The lens applies parameter changes by systematically varying the radius of curvature in the peripheral defocus area, creating a gradient from the central zone outward. This continuous parameter variation achieves effective myopia control through optimized optical path differences while maintaining a relatively simple overall lens structure that can be manufactured using conventional techniques with adjusted surface profiles.
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 effectively reduces myopia development by ensuring central image points are projected on the retina's central area and peripheral image points exhibit a myopic shift, mitigating the issue of irreducible peripheral hyperopic defocus common in existing rigid corneal contact lenses.
Implementation Method 1
a rigid contact lens comprising a front surface optical area and a back surface optical area wherein the front surface optical area includes a central optical zone and a peripheral defocus area around the central optical zone
Data Source
AI summary
A rigid corneal contact lens comprises a front-surface optical zone and a back-surface optical zone: the front-surface optical zone comprises a front-surface central zone (1) and a defocusing zone (2) at the periphery of the front-surface central zone (1); the front-surface central zone (1) is spherical; the defocusing zone (2) has a radius of curvature decreasing from the outside of the front-surface central zone (1) continuously and a minimum radius of curvature which ranges from 95% to 50% of the radius of curvature of the front-surface central zone (1). Because of the structure of a human eye, the phenomenon of peripheral hyperopic defocus exist in human eyes, that is, central image points for an image are projected on macula foveal of retina and peripheral image points are projected behind retina. As shown in experimental evidences, peripheral hyperopic defocus is the main cause of myopia development which can be moderated by restraining peripheral hyperopic defocus. In this present disclosure, a rigid corneal contact lens featuring stronger refractive power at the lens's periphery than at the lens's central area contributes to moderating peripheral hyperopic defocus for myopia control.