Low Water Content Soft Contact Lens with Acidic-Base Polymer Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional low water content soft contact lenses face issues with adhesion to the cornea, discomfort due to dryness, and a risk of bacterial growth, while also being challenging to produce with high oxygen permeability and mechanical properties.
Innovation Solution
A medical device comprising a low water content soft lens with a layer of acidic and basic polymers formed on a base material, using a monofunctional monomer component with a polymerizable functional group and a silicone moiety, and a polysiloxane compound with multiple polymerizable functional groups, which is produced through a method involving alternating coatings of acidic and basic polymer solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a low water content soft contact lens is made using conventional hydrogel materials, then the lens contains water which causes vaporization and dryness, but the lens structure becomes simple and easy to manufacture
Solution Approach 1:
The patent uses a composite material system consisting of a polysiloxane base material combined with surface-modified layers. The base material contains polysiloxane units providing oxygen permeability, while surface layers are grafted with hydrophilic polymers to reduce dryness. This composite structure resolves the contradiction by combining materials with complementary properties: the polysiloxane provides structural integrity and oxygen transmission, while the hydrophilic surface layers prevent water vaporization and discomfort.
Solution Approach 2:
The patent applies local quality modification by maintaining a hydrophobic, oxygen-permeable bulk material while creating a hydrophilic surface layer. The surface is specifically modified with grafted hydrophilic polymers or coating layers that have different properties from the bulk. This allows the lens interior to maintain high oxygen permeability while the surface provides moisture retention and comfort, resolving the contradiction between simple structure and reduced dryness.
2Reliability
If silicone rubber is used to create a highly oxygen permeable low water content lens, then oxygen permeability is improved, but the lens exhibits excessive resilience causing adhesion to the cornea and peeling of hydrophilized layers
Solution Approach 1:
The patent modifies the physical and chemical parameters of silicone rubber by incorporating hydrophilic polymer grafts or coating layers. The base polysiloxane provides high oxygen permeability, while the surface modification changes the surface energy and wettability parameters. This reduces the excessive resilience and adhesion problems while maintaining oxygen permeability, as the hydrophilic surface layers act as a buffer between the hydrophobic bulk and the cornea.
Solution Approach 2:
The patent introduces hydrophilic polymer layers as intermediary substances between the hydrophobic polysiloxane bulk and the corneal surface. These intermediate layers mediate the interaction by providing a hydrophilic interface that reduces direct adhesion between the hydrophobic lens material and the cornea, while also preventing peeling of surface layers through proper bonding to the bulk material.
3Reliability
If polysiloxane with multiple polymerizable functional groups is used, then flexibility and oxygen permeability are improved, but tackiness remains on the surface after polymerization causing adhesion to the cornea
Solution Approach 1:
The patent extracts or removes the problematic tackiness from the polymerized surface through surface modification treatments. After polymerization of the polysiloxane base material, the surface is treated with hydrophilic coatings or grafted layers that replace the tacky surface with a non-tacky, hydrophilic interface. This extraction of the harmful surface property while preserving the bulk material's flexibility and oxygen permeability resolves the contradiction.
4Object-affected harmful factors
If conventional LbL coating method with 4-20 layers is used, then surface properties are improved, but the production process becomes complex and costly
Solution Approach 1:
The patent merges multiple coating steps into a single integrated surface modification process. Instead of applying 4-20 alternating layers through complex LbL coating, the invention uses a single-step or reduced-step process where hydrophilic polymers are grafted directly onto the polysiloxane surface or a simplified coating layer is applied. This merging of steps maintains the desired surface wettability and lubricity while dramatically reducing production complexity and cost.
Solution Approach 2:
The patent performs preliminary surface activation or functionalization of the polysiloxane base material before final coating application. By pre-modifying the surface with reactive groups or activating treatments, the subsequent coating step becomes more efficient and requires fewer layers. This preliminary action reduces the total number of coating steps needed while achieving the same surface properties, thereby simplifying the production process.
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 lens exhibits improved wettability, lubricity, and mechanical properties, reducing adhesion to the cornea, minimizing bacterial growth risk, and achieving softness with breakage resistance, while simplifying the production process.
Implementation Method 1
a layer made of an acidic polymer and a basic polymer is formed on at least a part of a low water content soft base material
Implementation Method 2
a copolymer containing a monofunctional monomer component M having one polymerizable functional group and one silicone moiety per molecule
Implementation Method 3
a copolymer containing a monofunctional monomer component M having one polymerizable functional group and one silicone moiety per molecule
Data Source
Figure 1~2
Figure 3
AI summary
To provide a medical device which is excellent in wettability and lubricity and is also scarcely broken since it is soft, by a medical device in which a layer made of an acidic polymer and a basic polymer is formed on at least a part of a surface of a low water content soft base material, the low water content soft base material containing, as a main component, a copolymer containing a monofunctional monomer component M having one polymerizable functional group and one silicone moiety per molecule.