Coated Contact Lens Coating Coverage Evaluation Method
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Solution Overview
Problem
There is a need for a method to determine the uniformity and completeness of a lubricious coating on polyvinylalcohol-based contact lenses, as existing methods lack precision in ensuring the coating is covalently attached and uniformly distributed across the lens surface, affecting surface lubricity and wearer comfort.
Innovation Solution
A method involving a hydrophilic marker polymer with reactive groups and a dye tag moiety is used, where the coated contact lens is contacted with an aqueous solution of this polymer at a specific pH to covalently attach the marker through 6-membered acetal rings, and the attachment is optically evaluated to assess coating coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lubricious coating is applied to enhance surface lubricity, then surface lubricity is improved, but it becomes difficult to determine coating uniformity and completeness
Solution Approach 1:
The patent applies a dye-tagged marker polymer that exhibits color changes or fluorescent properties when it covalently attaches to the contact lens surface. This allows the coating uniformity to be visually detected and measured through optical methods, directly resolving the contradiction by providing a measurable indicator without compromising the lubricious coating's performance.
Solution Approach 2:
The marker polymer acts as an intermediary substance that competes with the lubricious coating for attachment sites on the contact lens. By observing where the marker polymer attaches (indicated by its dye tag), one can infer the completeness and uniformity of the lubricious coating, thus enabling measurement without directly measuring the coating itself.
2Ease of manufacture
If conventional coating methods are used, then coating application is simplified, but coating homogeneity and uniformity cannot be precisely controlled
Solution Approach 1:
The dye-tagged marker polymer provides immediate visual feedback about coating coverage and uniformity. This feedback mechanism allows manufacturers to adjust coating parameters in real-time or between batches to achieve desired homogeneity, resolving the contradiction between ease of manufacture and manufacturing precision.
Solution Approach 2:
The method uses a marker polymer with predetermined dye tags that are applied in the same coating process. This preliminary indication of coverage allows for verification and adjustment before final product completion, ensuring homogeneity without complicating the manufacturing process.
3Productivity
If coating completeness is not verified, then production time is reduced, but wearer comfort is compromised
Solution Approach 1:
The visual color or fluorescence indication provided by the dye-tagged marker polymer allows for rapid inspection of coating completeness. This quick visual verification method maintains high production speeds while ensuring that only properly coated lenses proceed to packaging, thus preserving wearer comfort without sacrificing productivity.
Solution Approach 2:
The patent replaces complex mechanical or chemical verification methods with simple optical detection of the dye-tagged marker. This substitution enables rapid quality assurance that does not add significant time to the production process while reliably ensuring coating completeness for wearer comfort.
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
This method allows for precise determination of coating completeness and uniformity, ensuring enhanced surface lubricity and improved wearer comfort by confirming the covalent attachment of the lubricious coating across the contact lens surface.
Implementation Method 1
covalently attach the marker polymer onto the coated polyvinylalcohol-based hydrogel contact lens through 6-membered acetal rings
Implementation Method 2
covalently attach the marker polymer onto the coated polyvinylalcohol-based hydrogel contact lens through 6-membered acetal rings
Implementation Method 3
determining whether marker polymer is (covalently) attached to the surface of the treated contact lens
Data Source
AI summary
The invention provides a method for determining whether a coated contact lens is completely covered by a covalently bonded coating, comprising the steps of (1) providing a coated polyvinylalcohol-based hydrogel contact lens wherein the polyvinylalcohol-based hydrogel lens body is composed of a polymer comprising at least 50% by mole of repeating units of vinyl alcohol, comprising a lubricious coating covalently attached to the lens body, (2) contacting the coated polyvinylalcohol-based hydrogel contact lens with an aqueous solution of a hydrophilic marker polymer for obtaining a treated contact lens, the hydrophilic marker polymer having reactive groups ofin which R1 is methyl or ethyl and R2 is hydrogen or a C1-C4 alkyl and a dye tag moiety, at a pH of 4.0 or less for a contacting time to covalently attach the marker polymer onto the coated polyvinylalcohol-based hydrogel contact lens through 6-membered acetal rings, (3) determining whether marker polymer is (covalently) attached to the surface of the treated contact lens.