Silicone Hydrogel Contact Lens Packaging for Wettability Improvement
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Solution Overview
Problem
Silicone hydrogel contact lenses suffer from low surface wettability due to their hydrophobicity, leading to deposit build-up and discomfort, and existing methods to enhance wettability are costly or require additional manufacturing steps.
Innovation Solution
A packaging solution containing hydroxyalkyl cellulose, such as hydroxyethyl cellulose, is used to immerse silicone hydrogel contact lenses during autoclaving, allowing the lenses to absorb the cellulose, thereby increasing their wettability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicone hydrogel materials are used for contact lenses, then oxygen permeability is improved, but surface wettability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the packaging solution by incorporating hydroxyalkyl cellulose at specific concentrations (0.01-5.0 wt%). This parameter change allows the silicone hydrogel contact lens to absorb hydrophilic substances during autoclaving, thereby improving surface wettability without altering the bulk oxygen permeability properties of the lens material.
Solution Approach 2:
The patent introduces hydroxyalkyl cellulose as an intermediary substance in the packaging solution. This intermediary mediates between the hydrophobic silicone hydrogel lens material and the aqueous environment, facilitating improved wettability through absorption during autoclaving while maintaining the lens's inherent oxygen permeability.
2Reliability
If custom siloxane monomers with hydrophilic groups are used, then surface wettability is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs inexpensive, readily available hydroxyalkyl cellulose (such as hydroxyethyl cellulose or hydroxypropyl methylcellulose) in the packaging solution rather than costly custom-synthesized hydrophilic siloxane monomers. This disposable packaging approach achieves the desired wettability improvement without requiring expensive material modifications or additional manufacturing steps.
Solution Approach 2:
The patent changes the packaging solution composition parameters to include hydroxyalkyl cellulose at optimized concentrations (0.01-5.0 wt%), providing a cost-effective alternative to modifying the lens material itself with expensive hydrophilic monomers.
3Reliability
If plasma treatment or hydrophilic coatings are applied, then surface wettability is improved, but device complexity increases
Solution Approach 1:
The patent merges the wettability enhancement function with the existing autoclaving sterilization process. By incorporating hydroxyalkyl cellulose into the packaging solution, the treatment occurs simultaneously with standard autoclaving, eliminating the need for separate plasma treatment or coating application steps.
Solution Approach 2:
The contact lens performs self-treatment by absorbing hydroxyalkyl cellulose from the packaging solution during autoclaving. This self-service mechanism eliminates the need for external coating application equipment or complex multi-step manufacturing processes.
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 absorption of hydroxyalkyl cellulose during autoclaving significantly improves the surface wettability of silicone hydrogel contact lenses, reducing the sessile drop contact angle and minimizing deposit build-up.
Implementation Method 1
a contact lens immersed in the packaging solution, wherein the contact lens comprises a silicone hydrogel and an extractable amount of the hydroxyalkyl cellulose embedded in the silicone hydrogel
Implementation Method 2
an autoclaved contact lens package comprising: (a) a packaging solution comprising a hydroxyalkyl cellulose
Data Source
AI summary
A silicone hydrogel contact lens is described comprising an extractable amount of a hydroxyalkyl cellulose embedded in the silicone hydrogel. The presence of the hydroxyalkyl cellulose in the silicone material improves the wettability of the contact lens.