Contact Lens Packaging with Tris Buffer and Surfactant
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Solution Overview
Problem
Contact lenses often cause discomfort due to dryness and eye irritation, particularly if not adequately wetted, and existing packaging solutions do not effectively prevent lens sticking and folding, leading to adverse effects during wear.
Innovation Solution
A packaging system using a sealed container with an aqueous solution of tris(hydroxymethyl)aminomethane or its salt, maintaining an osmolality of at least 200 mOsm/kg and a pH between 6 to 9, which provides a buffering system for improved stability and comfort, including the use of additional buffer agents, polysaccharides, and non-ionic surfactants to create an ophthalmically safe and sterile environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If saline or deionized water is used to store contact lenses in blister-packs, then the lenses are kept hydrated, but the lenses tend to stick to themselves and to the lens package, causing folding and discomfort
Solution Approach 1:
The patent modifies the chemical composition parameters of the packaging solution by incorporating specific buffering agents (phosphate, citrate, or borate buffers) and surfactants (poloxamers or polysorbates) in controlled concentrations. This changes the solution's properties to reduce surface tension and prevent lens sticking while maintaining hydration, thereby resolving the contradiction between keeping lenses hydrated and preventing them from sticking to the package.
2Duration of action of moving object
If contact lenses are worn for extended periods, then convenience is improved, but dryness and eye irritation increase, particularly towards the end of the day
Solution Approach 1:
The patent applies preliminary action by incorporating buffering agents and surfactants into the packaging solution before the lens is worn. These agents pre-condition the lens surface and create a protective environment that maintains lens hydration and reduces surface tension. This preliminary preparation prevents dryness and irritation during extended wear, allowing longer comfortable use without requiring frequent wetting drops.
3Ease of operation
If lens material is made more hydrophilic to improve comfort, then wetting is enhanced, but lens sticking to the package increases
Solution Approach 1:
The patent introduces surfactants (poloxamers or polysorbates) as intermediary substances in the packaging solution. These surfactants act as mediators between the hydrophilic lens material and the packaging surface, reducing surface tension and preventing direct adhesive contact between the lens and package. This allows the lens to remain well-wetted and comfortable while preventing sticking through the intermediary action of the surfactant molecules.
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 enhances the comfort and extended wear of contact lenses by maintaining lens hydration and preventing irritation, ensuring the solution is stable, safe, and free from microbial contamination, thus providing a better user experience.
Implementation Method 1
the solution has an osmolality of at least about 200 mOsm/kg
Implementation Method 2
an aqueous packaging solution comprising tris(hydroxymethyl)aminomethane or a salt thereof; wherein the solution has an osmolality of at least about 200 mOsm/kg and a pH in the range of about 6 to about 9
Data Source
AI summary
A packaging system for storing ophthalmic devices such as contact lenses and methods for packaging such ophthalmic devices with solutions is disclosed. The packaging system contains an unused, ophthalmic device in an aqueous packaging solution comprising tris(hydroxymethyl)aminomethane or a salt thereof; wherein the solution has an osmolality of at least about 200 mOsm/kg and a pH in the range of about 6 to about 9.