Low Water Contact Lens Surface Layer for Adhesion Control
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Solution Overview
Problem
Low water content soft contact lenses face issues with adhesion to the cornea, bacterial growth, and inadequate lacrimal fluid exchange, while existing methods are complex and costly to produce.
Innovation Solution
A low water content soft contact lens with a water content of 1% or less, featuring a tensile elastic modulus between 100 kPa and 2000 kPa, and a surface layer composed of an acidic and basic polymer, which enhances oxygen permeability, wettability, and lubricity, reducing adhesion and bacterial risk, and allowing for simple and cost-effective production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low water content soft contact lens is made to improve oxygen permeability and reduce bacterial growth risk, then oxygen permeability and hygiene are improved, but the lens becomes adhesive to the cornea and causes discomfort
Solution Approach 1:
The patent applies local quality by creating a surface layer with different properties than the bulk material. The contact lens has a low water content bulk (1-50%) for high oxygen permeability, while the surface layer (50-90% water content) provides hydrophilicity and anti-adhesion properties. This spatial differentiation of material properties resolves the contradiction between oxygen permeability and corneal comfort.
Solution Approach 2:
The patent uses composite materials by combining a low water content polymer matrix (for oxygen permeability) with a surface layer containing hydrophilic polymers or surfactants (for reduced adhesion). This composite structure integrates the benefits of both material types: the bulk provides oxygen transmission while the surface provides comfort and prevents sticking.
2Ease of operation
If a hydrogel material with high water content is used to improve comfort and wettability, then wettability and comfort are improved, but the lens becomes prone to bacterial contamination and evaporation
Solution Approach 1:
The patent applies local quality by concentrating hydrophilic components (hydrophilic polymers or surfactants) in the surface layer rather than distributing them throughout the bulk. This creates a localized hydrophilic zone that provides wettability and comfort where needed (at the cornea interface) while keeping the bulk material low water content for bacterial resistance and evaporation prevention.
3Ease of operation
If conventional LbL coating methods are used to form multi-layered structures, then surface properties are improved, but the production process becomes complex and costly
Solution Approach 1:
The patent merges the surface modification step with the lens manufacturing process itself. Rather than applying separate LbL coatings after lens formation, the surface layer is created during the polymerization process by incorporating hydrophilic monomers or surfactants into the mold or polymerization mixture. This integration eliminates multiple coating steps and reduces production complexity.
Solution Approach 2:
The patent applies preliminary action by preparing the surface layer components (hydrophilic monomers or surfactants) in advance and incorporating them into the polymerization system before lens formation. This preliminary preparation allows the surface properties to be established during the main manufacturing process rather than requiring subsequent complex coating operations.
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 maintains mechanical properties, reduces corneal adhesion, promotes effective lacrimal fluid exchange, and minimizes bacterial growth, providing comfort and soundness of the eye while being economical to produce.
Implementation Method 1
a layer made of an acidic polymer and a basic polymer is formed on at least a part of a surface of the base material
Implementation Method 2
since the low water content soft contact lens made of the hydrogel material contains water, there arises a phenomenon in which water is vaporized from the contact lens
Data Source
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AI summary
Disclosed is a low water content soft contact lens to be worn in the eye, wherein a pattern promoting the exchange of lacrimal fluid between the low water content soft contact lens and the eye is formed. The present invention can significantly reduce or avoid a phenomenon of adhesion to a surface when contacted with a surface outside or inside the body, which has hitherto been regarded as a problem in a conventional contact lens.