Soft Contact Lens Design for Keratoconus Using Elastic Modulus Control
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Solution Overview
Problem
Conventional rigid contact lenses are difficult to fit for patients with keratoconic defects due to conflicting requirements of optical performance, comfort, and avoiding damage to thinning corneal tissue, leading to inefficiencies and discomfort in the fitting process.
Innovation Solution
A method for designing soft contact lenses with a central optic zone and peripheral zone, where the back surface is defined for a satisfactory corneal fit and the front surface is optimized to correct vision defects, using a material with a Young's modulus of 0.08 to 0.40 MPa and a junction thickness of 0.15-0.40 mm, incorporating sector management control for improved fit and optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid contact lenses are used to maintain optical performance over distorted corneas, then the lens can bridge over corneal distortions, but the lens causes trauma to thinning corneal tissue and is difficult to fit
Solution Approach 1:
The patent changes the physical parameters of the contact lens by using soft materials with specific elastic modulus ranges (0.08-0.40 MPa) and controlled thickness ranges (0.15-0.40 mm), transforming the lens from rigid to soft while maintaining optical performance through precise parameter control
Solution Approach 2:
The patent employs flexible soft contact lens materials that can conform to irregular corneal surfaces, replacing rigid structures with flexible shells that adapt to the corneal geometry while providing optical correction
2Stability of the object's composition
If rigid contact lenses are used to correct vision defects, then the lens maintains its form on the eye, but the fitting process is extremely difficult and time-consuming
Solution Approach 1:
The patent modifies the material properties by selecting soft materials with specific elastic modulus and thickness parameters, enabling the lens to maintain stability through material properties rather than rigidity, thus simplifying the fitting process
3Object-affected harmful factors
If soft contact lenses are used to reduce corneal trauma, then the lens is more comfortable for the patient, but the lens may not maintain sufficient optical performance over distorted corneas
Solution Approach 1:
The patent optimizes the balance between softness and optical performance by precisely controlling the elastic modulus (0.08-0.40 MPa) and thickness (0.15-0.40 mm) parameters, ensuring the lens remains soft for comfort while maintaining sufficient structural integrity for optical correction
Solution Approach 2:
The patent addresses the optical performance issue by controlling the lens thickness dimension, ensuring adequate thickness to maintain form over the cornea while keeping the material soft, thus solving the contradiction through dimensional control
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 method provides unexpectedly good optical performance and comfort for patients with keratoconic conditions using soft contact lenses with specific modulus and thickness ranges, reducing the need for multiple trial lenses and minimizing corneal trauma.
Implementation Method 1
a soft contact lens... made of a substance having a Young's modulus in the range 0.08 to 0.40 MPa
Implementation Method 2
the anterior surface of the contact lens replaces the front of the cornea and becomes the main refractive element of the patient's eye
Data Source
AI summary
The invention relates to a method of designing a soft contact lens, said lens having a central optic zone and with a peripheral zone around the central optic zone;the method comprising the steps of:(a) defining a back surface of the lens which is a satisfactory fit to the surface of a subject's cornea;(b) defining a front surface of the lens over at least the central optic zone, which surface is selected so as to ameliorate the subject's vision defects;(c) checking that the lens meets a desired range of thickness values at one or more selected parts of the lens and, if not, recalculating the front surface over at least the central optic zone so as to meet said desired thickness value range,wherein the lens is to be made of a substance having a Young's modulus in the range 0.08 to 0.40 MPa, and wherein the junction thickness of the lens is in the range 0.15-0.40 mm.