Spin-Assisted Layer-by-Layer Polymer Coatings for IOL Cartridge Friction
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Solution Overview
Problem
Current intraocular lens (IOL) cartridge coatings face issues with friction, lubricant degradation, and coating stability, leading to difficulties in implantation and potential damage to the lens, especially with high friction forces and the risk of lubricant transfer affecting optical properties.
Innovation Solution
Spin-assisted layer-by-layer polymer coatings using positively and negatively charged polymers, applied via plasma-treated cartridges, to create a stable, lubricious, and biocompatible surface that facilitates easy IOL delivery through small incisions without damage, maintaining coating integrity during long-term storage and sterilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If fatty acid esters are added as lubricant additive to the cartridge material, then the friction force is reduced and IOL implantation is facilitated, but the lubricant rises to the surface over time and adheres to the IOL surface, damaging its optical properties
Solution Approach 1:
The harmful lubricant substance (fatty acid esters) is extracted from the cartridge material composition. Instead of adding lubricants to the cartridge material, the patent applies a separate coating layer to the cartridge inner surface that provides lubrication without risking transfer to the IOL. This separates the lubrication function from the cartridge material itself.
Solution Approach 2:
A coating layer acts as an intermediary between the cartridge and the IOL. This coating provides the necessary lubrication while preventing direct contact between the cartridge material and IOL surface, thus avoiding optical property damage. The coating serves as a mediator that transfers lubrication without transferring harmful substances.
2Ease of operation
If viscoelastic gel is added between the lens surface and coated cartridge surface to facilitate sliding, then the lens can be delivered through the cartridge, but the gel may scratch and deform the lens or change its optical properties
Solution Approach 1:
The patent changes the physical and chemical parameters of the coating layer to optimize lubrication while preventing lens damage. By controlling the coating's composition, thickness, and properties, it provides sufficient lubrication for lens delivery without the harmful effects of viscoelastic gel. The coating parameters are adjusted to ensure biocompatibility and lack of lens interaction that would cause deformation.
3Force
If a coating is applied to the cartridge inner surface to reduce friction, then IOL implantation is facilitated, but the coating may transfer to the IOL surface during long shelf life, affecting optical properties
Solution Approach 1:
The coating layer is designed to be stable and non-transferable during the product's shelf life. Instead of using temporary lubricants that may migrate, the patent employs a stable coating formulation that maintains its properties throughout storage. The coating is engineered to remain on the cartridge and not transfer to the IOL, ensuring long-term stability.
4Productivity
If high pressure is applied to push the folded IOL through the cartridge, then the lens can be implanted, but the IOL expands inside the cartridge due to friction force and becomes impossible to remove
Solution Approach 1:
The lubricating coating is applied to the cartridge inner surface before IOL insertion. This preliminary lubrication reduces friction force during the insertion process, allowing the IOL to be pushed through without requiring excessive pressure. The coating prevents the harmful expansion effect by reducing resistance from the outset.
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 provides a stable, lubricious coating that reduces injection force, prevents lens damage, and maintains coating adhesion to the cartridge, ensuring successful IOL delivery through small incisions with minimal coating transfer to the lens, even after long-term storage and sterilization.
Implementation Method 1
The inner surface of the cartridge is coated with a polymer-based coating material using a spin coating device
Implementation Method 2
The cartridges are subjected to plasma treatment before coating to ensure proper adhesion and biocompatibility
Implementation Method 3
Layer-by-layer (LBL) deposition is a very promising approach consisting of sequential immersion of a substrate into solutions of oppositely charged materials
Data Source
AI summary
Spin-assisted layer-by-layer polymer coatings are used as the inner surface coating material for intraocular lens cartridges and facilitate the implantation of intraocular lenses.