UV Absorber Stabilization in Ocular Lenses via Antioxidants
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Solution Overview
Problem
Existing methods for incorporating UV absorbers into ophthalmic devices, such as spectacle lenses, face challenges with insoluble residues and oxidative decomposition, leading to contamination and coloration issues, especially when using solvents or water-soluble UV absorbers.
Innovation Solution
An aqueous composition comprising a UV absorber and an effective amount of an antioxidant is used to prevent the formation of insoluble reaction and oxidative decomposition products, allowing for the production of stable UV absorber solutions without the need for solvents, suitable for various ocular devices like spectacle, contact, and intraocular lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If solvents are used to facilitate dissolution of UV absorber, then solubility is improved, but environmental safety and oxidative stability deteriorate
Solution Approach 1:
The patent changes the chemical parameters of the aqueous solution by adding antioxidants (such as ascorbic acid, sodium sulfite, or EDTA) to modify the oxidation-reduction potential and pH of the solution. This prevents oxidative decomposition of the UV absorber while maintaining water as the solvent, thus resolving the contradiction between solubility and oxidative stability.
2Ease of manufacture
If water-soluble UV absorbers are used, then ease of manufacture is improved, but formation of insoluble oxidation products increases
Solution Approach 1:
The patent applies preliminary action by adding antioxidants to the aqueous solution before incorporating the UV absorber. This preemptive measure prevents oxidative decomposition from occurring during the imbibition process, thereby preventing the formation of insoluble oxidation products while maintaining the ease of using water-soluble UV absorbers.
3Reliability
If UV absorber solution is used for imbibition, then UV protection is achieved, but contamination and coloration of lenses occur
Solution Approach 1:
The patent introduces antioxidants as intermediary substances that mediate between the UV absorber and oxygen in the aqueous solution. These antioxidants preferentially react with oxygen or free radicals, protecting the UV absorber from oxidative decomposition and preventing the formation of colored decomposition products that would contaminate the lenses.
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 effectively prevents the formation of insoluble reaction products and oxidative decomposition, ensuring the stability and effectiveness of UV absorption in ocular devices, maintaining their clarity and functionality over time.
Implementation Method 1
insoluble reaction products and oxidative decomposition
Implementation Method 2
UV absorbers are desirable... containing UV absorbers... capable of absorbing or screening out UV radiation
Data Source
AI summary
The invention provides UV absorber solutions that do not require use of a solvent to prevent formation of insoluble reaction products. The invention is useful in the manufacture of ocular devices including spectacle, contact and intraocular lenses, but may find its greatest utility in the manufacture of spectacle lenses.