Light Adjustable Intraocular Lens Polymerization Control
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Solution Overview
Problem
Light Adjustable Lenses (LALs) face challenges with undesirable optical power drift due to incomplete lock-in procedures and exposure to sunlight, leading to unintended shifts and tilts post-surgery, which affect visual acuity.
Innovation Solution
Incorporating a polymer silicone network with a mobile macromer, switchable and non-switchable ultraviolet absorbers, and a photoinitiator, along with a radical scavenger, to control polymerization and minimize optical power changes by optimizing oxygen concentration and reaction rates, allowing for single lock-in procedures and enhanced UV protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a lock-in procedure is performed to deactivate photopolymerizable material, then optical stability is improved, but incomplete deactivation leads to power drift
Solution Approach 1:
The patent modifies chemical parameters by introducing a radical scavenger component that changes the reaction dynamics. This component alters the polymerization kinetics to ensure complete deactivation of photopolymerizable material, preventing power drift while maintaining optical stability. The radical scavenger modifies the chemical environment to achieve more thorough polymerization completion.
Solution Approach 2:
The patent creates a composite photopolymerization system combining photoinitiator, mobile macromer, and radical scavenger components. This composite approach allows the system to achieve both optical stability through controlled polymerization and complete deactivation through the synergistic interaction of multiple components, eliminating residual reactive material that causes power drift.
2Adaptability or versatility
If photopolymerizable material is used for light adjustment, then optical power can be corrected, but unintended polymerization causes power drift
Solution Approach 1:
The radical scavenger acts as an intermediary component that mediates between the photoinitiator and mobile macromer. It controls the polymerization process by temporarily capturing radicals and then releasing them in a controlled manner, preventing unintended polymerization while allowing desired optical power adjustment through controlled illumination.
Solution Approach 2:
The patent changes the kinetic parameters of the polymerization process by introducing the radical scavenger. This modifies the reaction rates and activation thresholds, creating a more selective polymerization process that responds only to controlled illumination while resisting unintended activation from ambient light or heat.
3Stability of the object's composition
If multiple lock-in procedures are performed to ensure complete deactivation, then power drift is reduced, but treatment time and patient burden increase
Solution Approach 1:
The radical scavenger is incorporated into the lens material in advance, preparing the chemical environment for complete polymerization. This preliminary preparation ensures that a single lock-in procedure will be sufficient for complete deactivation, eliminating the need for multiple treatment sessions and reducing patient burden while maintaining power drift reduction.
Solution Approach 2:
The patent modifies the chemical composition parameters by adding the radical scavenger at specific concentrations. This parameter change alters the polymerization completion characteristics, enabling single-procedure lock-in to achieve complete deactivation that previously required multiple procedures, thereby reducing treatment time while maintaining stability.
4Speed
If oxygen concentration is increased to control polymerization, then polymerization rate is reduced, but oxygen availability may be limited
Solution Approach 1:
The radical scavenger serves as an intermediary that decouples the relationship between oxygen concentration and polymerization rate control. It provides an alternative mechanism for regulating polymerization kinetics through radical capture and release, allowing polymerization rate control without relying solely on oxygen availability, thus overcoming the limitation of oxygen supply in the aqueous environment.
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 stabilizes the optical properties of LALs, reducing long-term power drift and eliminating the need for multiple lock-in procedures, enhancing patient comfort and visual acuity by minimizing unintended polymerization and zone formation.
Implementation Method 1
a photoinitiator which is activated by a shaped UV illumination induces a polymerization of the mobile macromer
Implementation Method 2
a front protection layer, including a switchable ultraviolet absorber
Implementation Method 3
a ratio R of the oxygen concentration [O2] times an oxygen-driven photoinitiator quench rate kq over a mobile macromer concentration [MM] times a photoinitiator-driven polymerization add rate ka, R=kq [O2]/ka [MM], is greater than 10
Implementation Method 4
The LAL includes a radical scavenger or an antioxidant
Data Source
AI summary
Light Adjustable Lenses (LALs) are described that suppress unintended optical power drift. These LALs comprise a polymer silicone network, infused with a mobile macromer, a non-switchable ultraviolet absorber, a photoinitiator, and a front protection layer, including a switchable ultraviolet absorber. The LAL is light adjustable by a shaped illumination activating the photoinitiator which induces a polymerization of the mobile macromer, thereby changing an optical power of the LAL. The LAL can accommodate an 0.5-20 ppm oxygen concentration; and a ratio of the oxygen concentration times an oxygen-driven photoinitiator quench rate over a mobile macromer concentration times a photoinitiator-driven polymerization add rate is greater than 10. Some of these LALs include a non-switchable ultraviolet absorber in the front protection layer; or a radical scavenger; or a monofunctional, or sterically hindered mobile macromer; or a switchable photoinitiator, or an anchored photoinitiator.