Volume-Excluding Polymer Layer for Silicone Hydrogel Lens Mucin Control
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Solution Overview
Problem
Silicone hydrogel contact lenses suffer from mucin ball formation due to the shearing force between the eyelid and the lens material, leading to comfort issues and long-term effects that are not fully understood, and existing solutions do not adequately address the wettability and oxygen permeability of these lenses.
Innovation Solution
A composition comprising a hydrated polymer with volume-excluding polymers, specifically hydratable polyanions that form a layer on the lens surface, acting as an osmotic driver to maintain water balance and prevent dehydration, thereby improving comfort and reducing mucin ball formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicone materials are used to increase oxygen permeability, then oxygen transmission to the eye is improved, but wettability deteriorates and mucin ball formation occurs
Solution Approach 1:
The patent combines silicone materials with volume-excluding polymers (such as polyacrylic acid, polyacrylamide, or polyvinyl alcohol) to create a composite contact lens material. This composite structure allows the silicone component to provide high oxygen permeability while the volume-excluding polymer component provides hydrophilicity and prevents mucin ball formation by excluding mucin from the lens surface.
Solution Approach 2:
The volume-excluding polymer acts as an intermediary layer on the silicone hydrogel surface. This intermediary layer mediates between the hydrophobic silicone material and the aqueous tear film, providing a hydrophilic interface that prevents mucin adhesion while allowing the underlying silicone to maintain its oxygen permeability.
2Quantity of substance
If silicone hydrogel material is used, then oxygen transmission is improved, but surface wettability deteriorates
Solution Approach 1:
The contact lens is constructed as a composite material where silicone hydrogel provides the oxygen permeability and a separate volume-excluding polymer layer provides the hydrophilic surface properties. This composite approach allows both high oxygen transmission and good surface wettability to coexist.
Solution Approach 2:
The volume-excluding polymer is applied specifically to the surface regions of the contact lens that require wettability, while the bulk silicone hydrogel material maintains its oxygen permeability properties. This local application of different properties allows optimization of each function in its appropriate location.
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 volume-excluding polymers enhance the wettability and oxygen permeability of silicone hydrogel contact lenses, reducing mucin ball formation and improving the overall comfort and wearability of the lenses.
Implementation Method 1
acting as an osmotic driver to maintain water balance and prevent dehydration
Implementation Method 2
hydratable polyanions that form a layer on the lens surface
Data Source
AI summary
The present invention relates to compositions comprising a polymeric substrate comprising at least one volume excluding polymer. In one embodiment, the present invention provides polymeric articles that are capable of acting as osmotic drivers. The articles are capable of maintaining a desired water balance by moving water in or out of a substrate to maintain cation concentration equilibrium between the substrate and its environment.