Wettable Silicone Hydrogel Contact Lens Composition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hydrogel contact lenses have poor oxygen permeability and low wettability due to their hydrophobic nature, making them unsuitable for biomedical applications without additional coatings, which complicates their manufacture and physiological performance.
Innovation Solution
A contact lens composition comprising at least 10 weight percent of silicone-containing monomers, 3-methacryloxypropyl tris(trimethylsiloxy)silane, N-vinyl pyrrolidone, and another non-ionic hydrophilic monomer, where N-vinyl pyrrolidone is present in sufficient amounts to form polyvinyl pyrrolidone homopolymer, eliminating the need for pre-polymerized PVP and reducing haze with small amounts of methacrylic acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicone-containing monomers are introduced to increase oxygen permeability, then oxygen permeability is improved, but wettability deteriorates due to hydrophobic nature
Solution Approach 1:
The patent uses a composite monomer system combining silicone-containing monomers (for oxygen permeability) with hydrophilic monomers (for wettability) to create a balanced contact lens material that achieves both oxygen permeability and adequate wettability without requiring external coatings
Solution Approach 2:
The patent optimizes the ratio and concentration of silicone-containing monomers versus hydrophilic monomers in the polymerization mixture to achieve the desired balance between oxygen permeability and wettability, adjusting compositional parameters to resolve the contradiction
2Ease of operation
If hydrophilic coatings are applied to improve wettability, then wettability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent incorporates hydrophilic monomers during the initial polymerization process to pre-establish wettability properties within the contact lens material itself, eliminating the need for subsequent coating steps and simplifying manufacturing
Solution Approach 2:
The contact lens material is designed to be self-sufficient by incorporating both oxygen-permeable and hydrophilic properties within the base polymer matrix, allowing the material to provide both functions without requiring external coatings or additional processing steps
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 solution produces wettable silicone hydrogel contact lenses with improved oxygen permeability and wettability without the need for hydrophilic coatings, simplifying manufacturing and enhancing physiological performance by ensuring good contact angles, water content, clarity, and surface quality.
Implementation Method 1
N-vinyl pyrrolidone is present in such an amount that the reaction product comprises polyvinyl pyrrolidone homopolymer
Implementation Method 2
Silicone-containing polymers generally have higher oxygen permeabilities than conventional hydrogels
Implementation Method 3
The suitability of a material for use in biomedical devices depends on the wettability of the material and its proclivity for adhesion or reaction with biological materials such as proteins and lipids
Implementation Method 4
A hydrogel is a hydrated cross-linked polymeric system that contains water in an equilibrium state
Data Source
AI summary
A contact lens formed of a composition comprising the reaction product of: A) at least 10 weight percent, based on the total composition weight excluding solvent, of at least one silicone-containing monomer of the formula I: where n is from 1 to 3, m is from 9 to 15, each a independently is C1-4 alkyl, and each b independently is C1-4 alkyl; B) at least 10 weight percent, based on the total composition weight excluding solvent, of 3-methacryloxypropyl tris(trimethylsiloxy)silane; C) N-vinyl pyrrolidone; and D) at least one other non-ionic hydrophilic monomer wherein the combined amount of A) and B) is at least 20 weight percent based on the total composition weight excluding solvent, and wherein the N-vinyl pyrrolidone (NVP) is present in such an amount that the reaction product comprises polyvinyl pyrrolidone (PVP) homopolymer.