Siloxane Hydrogel Contact Lens Composition for Oxygen Permeability
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Solution Overview
Problem
Hydrogel and silicone hydrogel contact lenses face challenges with low oxygen permeability and surface hydrophobicity, leading to bacterial growth and eye irritation.
Innovation Solution
A composition for manufacturing contact lenses comprising a siloxane macromer, a hydrophilic monomer, and a crosslinking agent, combined with an initiator, which are mixed and heated to form lenses with a hydrophilic surface, enhancing oxygen permeability and water content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If hydrophilic monomers are added to increase water content, then water content is improved, but lens strength and toughness deteriorate
Solution Approach 1:
The patent uses a composite material system combining siloxane macromers (for strength and oxygen permeability) with hydrophilic monomers (for water content). This composite approach allows achieving high water content (50-70%) while maintaining lens strength through the synergistic combination of hydrophobic siloxane backbone and hydrophilic monomer networks.
2Reliability
If water content is increased to improve oxygen permeability, then oxygen permeability is improved, but lens strength and toughness deteriorate
Solution Approach 1:
The siloxane-hydrophilic monomer composite structure enables high oxygen permeability through both water channels and siloxane domains, while the crosslinked network maintains mechanical strength. The dual-network structure provides multiple pathways for oxygen transport without sacrificing structural integrity.
Solution Approach 2:
The patent creates local hydrophilic regions (from hydrophilic monomers) and local hydrophobic regions (from siloxane macromers) within the lens matrix. This local quality differentiation allows oxygen to permeate through both water-rich and siloxane-rich domains, while the overall crosslinked structure maintains uniform mechanical strength throughout the lens.
3Reliability
If silicone polymeric material is used to improve oxygen permeability, then oxygen permeability is improved, but surface hydrophobicity increases leading to bacterial growth and eye irritation
Solution Approach 1:
The patent creates a heterogeneous structure where hydrophilic monomer clusters are distributed within the siloxane matrix. This local quality variation ensures that the lens surface and internal structure contain hydrophilic regions that prevent bacterial adhesion and reduce eye irritation, while siloxane regions maintain high oxygen permeability.
Solution Approach 2:
The composite of siloxane macromers and hydrophilic monomers creates a material that simultaneously exhibits oxygen permeability (from siloxane) and anti-fouling properties (from hydrophilic monomers). The synergistic combination resolves the contradiction between oxygen transport and surface biocompatibility.
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 resulting contact lenses exhibit improved oxygen permeability and high water content, reducing bacterial growth and eye irritation while maintaining lens integrity.
Implementation Method 1
a siloxane macromer, a hydrophilic monomer, a crosslinking agent and an initiator are mixed to form a mixture. Then, the mixture is injected into a mold of contact lens and heated to form contact lenses
Data Source
AI summary
A composition is provided for manufacturing contact lenses including a siloxane macromer represented by the following formula (I):wherein R1, R2 and R3 are independently C1-C4 alkyl groups, R4 is C1-C6 alkyl group, R5 is a residue obtained by removing NCO group from an aliphatic or aromatic diisocyanate, R6 and R7 are independently alkylene groups, and n is an integer of about 4-80, m is an integer of about 3-40; a crosslinking agent or a siloxane macromer represented by the following formula (II), wherein p is an integer of 4-80 and q is an integer of 3-40:and an initiator.