Silicone Hydrogel Contact Lens Coating for Antimicrobial Resistance
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Solution Overview
Problem
Silicone hydrogel contact lenses are susceptible to high deposition and accumulation of positively charged antimicrobials, leading to undesirable clinical symptoms such as diffuse corneal staining and product intolerance, due to the presence of a polyanionic anchoring layer.
Innovation Solution
A method for producing silicone hydrogel contact lenses with a crosslinked hydrophilic coating using a polymerization product of siloxane-containing vinylic monomers, polysiloxane vinylic crosslinkers, and hydrophilic vinylic monomers, followed by contacting with polymethacrylic acid and polyamidoamine-epichlorohydrin solutions to form a durable non-silicone hydrogel coating, reducing susceptibility to antimicrobial deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a polyanionic anchoring layer is applied onto a silicone hydrogel contact lens, then the lens surface becomes more hydrophilic and lubricious, but the lens becomes highly susceptible to deposition and accumulation of positively charged antimicrobials
Solution Approach 1:
The patent applies a composite coating structure consisting of a polyanionic anchoring layer combined with a partially-crosslinked hydrophilic polymeric material layer. This composite structure maintains the hydrophilic and lubricious properties from the polyanionic layer while the crosslinked hydrophilic polymer layer reduces antimicrobial deposition, thus resolving the contradiction between surface lubricity and antimicrobial resistance
Solution Approach 2:
The patent modifies the surface properties by controlling the degree of crosslinking of the hydrophilic polymeric material (from 0% to 50% or higher) and adjusting the composition ratio between the polyanionic polymer and hydrophilic polymer. These parameter changes enable optimization of both lubricity and antimicrobial resistance properties
2Object-affected harmful factors
If a crosslinked hydrophilic coating is formed on silicone hydrogel contact lenses, then antimicrobial deposition is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies the polyanionic anchoring layer in advance before applying the hydrophilic polymeric material. This preliminary action creates a stable foundation that simplifies the subsequent coating process and ensures proper adhesion of the crosslinked hydrophilic layer, reducing overall process complexity despite the multiple steps involved
Solution Approach 2:
The polyanionic anchoring layer serves as an intermediary between the silicone hydrogel lens and the crosslinked hydrophilic coating. This intermediary layer facilitates proper adhesion and provides a platform for the crosslinked coating, simplifying the interface between incompatible materials and streamlining the manufacturing process
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 results in a durable coating that minimizes the accumulation of positively charged antimicrobials, enhancing the lubricity and stability of the contact lens surface, thereby reducing clinical symptoms and improving user comfort.
Implementation Method 1
a crosslinked hydrophilic coating thereon
Data Source
AI summary
The invention is related to a method for producing silicone hydrogel contact lenses with having a stable coating thereon. A method of the invention comprises a water-based coating process (step) for forming a relatively-stable base coating of a homo- or copolymer of acrylic acid or C1-C3 alkylacrylic acid onto a silicone hydrogel contact lens made from a lens formulation comprising from about 35% to about 60% by weight of N-vinylpyrrolidone.