Acrylate-acrylamide copolymers for foldable IOLs
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Solution Overview
Problem
Existing hydrophobic acrylic materials for intraocular lenses (IOLs) face issues with tackiness, glistenings, and refractive index, which affect manufacturing, handling, and optical performance, while conventional materials either have low refractive index or are prone to explosive unfolding.
Innovation Solution
Development of acrylate-acrylamide copolymers that are rigid and glassy in the dry state but become soft and deformable upon hydration, with a high refractive index and minimal glistenings, achieved by specific monomer ratios and polymerization processes, reducing surface tack and age-related degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydrogel materials are used for IOLs, then the material is soft and flexible, but the refractive index is low requiring thicker lens optics
Solution Approach 1:
The patent uses composite materials by combining hydrophobic acrylic monomers (for high refractive index) with hydrophilic monomers (for softness and flexibility). This creates a copolymer material that exhibits both high refractive index (1.44-1.48) and appropriate softness for foldable IOLs, resolving the contradiction between optical performance and mechanical flexibility.
2Illumination intensity
If conventional silicone materials are used for IOLs, then the refractive index is high, but the material unfolds explosively after being placed in the eye in a folded position
Solution Approach 1:
The patent changes the material parameters by using hydrophobic acrylic materials with specific glass transition temperatures (Tg between -10°C to +10°C) and controlled equilibrium water content (5-20%). These parameter adjustments enable the material to unfold slowly and controllably after implantation, avoiding explosive unfolding while maintaining high refractive index (1.44-1.48).
3Ease of operation
If soft hydrophobic acrylic materials are used to reduce tackiness, then handling is improved, but glistenings form in vivo affecting optical performance
Solution Approach 1:
The patent applies local quality by carefully controlling the distribution and concentration of hydrophilic monomer units within the hydrophobic acrylic matrix. By limiting hydrophilic monomer content to specific ranges (5-30 mol%) and using specific monomer types, the material achieves reduced surface tack for improved handling while minimizing glistening formation through localized hydrophilic domains that prevent water aggregation.
4Object-generated harmful factors
If PEG-containing polymerizable components are added to improve glistening resistance, then glistenings are reduced, but the refractive index decreases
Solution Approach 1:
The patent changes material parameters by selecting specific PEG chain lengths (n=2-10) and controlling PEG monomer concentration (1-20 mol%). By optimizing these parameters, the material achieves improved glistening resistance through the PEG component while maintaining acceptable refractive index (1.44-1.48) through the dominant hydrophobic acrylic matrix composition.
5Ease of manufacture
If acrylate-acrylamide copolymers are made rigid and glassy in dry state for easy handling, then manufacturing is improved, but the material must become soft upon hydration for foldable IOL application
Solution Approach 1:
The patent applies dynamics by designing a material with temperature- and hydration-dependent mechanical properties. The copolymer composition (hydrophobic acrylate with glassifying agent and hydrophilic acrylamide) creates a material that is rigid and glassy in the dry state for easy manufacturing and handling, but transitions to a soft, deformable state upon hydration (equilibrium water content 5-20%) to enable folding for minimally invasive implantation.
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 acrylate-acrylamide copolymers provide a material suitable for microincision applications with reduced surface tack, high refractive index, and minimal glistenings, ensuring stable and clear performance over time, suitable for wet-packed IOLs.
Implementation Method 1
acrylate-acrylamide copolymers which are rigid and glassy in dry state, and upon hydration, are soft and essentially free of glistenings
Data Source
AI summary
Acrylate-acrylamide copolymers are disclosed. They are rigid and glassy in dry state at room temperature (from about 23°C to about 28°C), but are soft and very deformable and have a high refractive index, a high glistening resistance and a low aging-related surface light scattering in fully hydrated state. They are particularly suitable for making wet-packed intraocular lenses (IOLs) which can be delivered through sub 2.0 mm incisions.