Hydrogel Contact Lens HEVL Absorber Blend With Low Yellowing
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Solution Overview
Problem
Existing contact lens formulations that incorporate high quantities of benzotriazole blue light blockers to reduce harmful light transmission often result in undesirable yellowing and affect the properties of the lens material, such as wettability and processing, necessitating a need for a radiation absorber package that provides effective blue light blocking without significant yellowing.
Innovation Solution
A combination of two different benzotriazole high energy, short wavelength visible light absorbers with distinct absorption properties is used in contact lens formulations, optionally including a benzophenone UV absorber, to achieve effective blue light blocking with minimal yellowing, using amounts not exceeding 2.7% by weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If large quantities of benzotriazole blue light blockers are included in contact lens formulations to substantially reduce light transmission in the 380-455 nm range, then blue light blocking effectiveness is improved, but yellowing of the lens occurs and lens properties such as wettability and processing are adversely affected
Solution Approach 1:
The patent changes the concentration parameter of benzotriazole blue light blockers from high levels (2% or more) to low levels (0.01-2.7%), and combines this with a specific pH parameter adjustment (pH 6.5-8.0) to achieve effective blue light blocking without yellowing while maintaining lens wettability and processing properties
Solution Approach 2:
The patent creates a composite radiation absorber package combining benzotriazole blue light blockers with other compatible compounds including benzophenone UV absorbers and triazine HEVL absorbers, where each component contributes to the overall blue light blocking function at optimized low concentrations, preventing yellowing while maintaining effectiveness
2Object-affected harmful factors
If large quantities of benzotriazole blue light blockers are included in contact lens formulations to substantially reduce light transmission in the 380-455 nm range, then blue light blocking effectiveness is improved, but lens processing and de-lensing from mould are hindered
Solution Approach 1:
The patent optimizes the concentration parameter of benzotriazole blue light blockers to low levels (0.01-2.7%) and adjusts the pH parameter to 6.5-8.0, which maintains effective blue light blocking while ensuring proper lens processing, casting, and de-lensing from mould without the adverse effects of high concentrations
3Object-affected harmful factors
If large quantities of benzotriazole blue light blockers are included in contact lens formulations to substantially reduce light transmission in the 380-455 nm range, then blue light blocking effectiveness is improved, but wettability of the hydrogel contact lens is reduced
Solution Approach 1:
The patent adjusts the concentration parameter of benzotriazole blue light blockers to low levels (0.01-2.7%) and optimizes the pH parameter to 6.5-8.0, which preserves effective blue light blocking while maintaining adequate lens wettability and comfort for the wearer
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 combination of benzotriazole absorbers effectively reduces blue light transmission by at least 40-50% in the 380-455 nm range without substantial yellowing, maintaining lens quality and aesthetics.
Implementation Method 1
Benzotriazole blue light blockers have been developed that selectively absorb light with wavelengths in the range of 380-455 nm
Implementation Method 2
Benzotriazole, benzophenone and triazine-containing compounds are known to absorb UV light
Data Source
AI summary
A hydrogel contact lens formulation for forming the polymeric body of a hydrogel contact lens comprising: a first high energy visible light (HEVL) absorber comprising a benzotriazole moiety and a second different high energy visible light (HEVL) absorber comprising a benzotriazole moiety, and a hydrogel contact lens obtained from the polymerisation of the formulation.