Embedded Hydrogel Contact Lens Insert Positioning Without Mold Posts
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Solution Overview
Problem
Existing methods for producing embedded hydrogel contact lenses with inserts face challenges in accurately positioning the inserts without forming small holes that trap bioburden and potential mechanical property alterations due to precuring and curing processes.
Innovation Solution
A method involving two lens-forming compositions with identical polymerizable components but different non-reactive diluents, where one is more viscous than the other, is used to precisely position inserts within a mold assembly, eliminating the need for positioning guides and precuring steps, ensuring homogeneous mechanical properties and avoiding bioburden trapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If positioning guides (posts) are used in molds during cast-molding process, then insert positioning precision is improved, but small holes are formed in resultant embedded hydrogel contact lenses that are susceptible to bioburden trapping
Solution Approach 1:
The patent removes the positioning guides (posts) from the mold system entirely. Instead of using physical guides that create holes, the invention uses a precured insert assembly with integrated positioning features that eliminate the need for separate positioning guides, thereby eliminating the source of bioburden trapping holes while maintaining positioning precision
Solution Approach 2:
The patent applies preliminary action by precuring the insert assembly before final lens formation. The insert is precured with positioning features already integrated into its structure, allowing it to be placed directly into the mold without requiring separate positioning guides. This preliminary preparation eliminates the need for post-positioning adjustments and guide structures that would create harmful holes
2Manufacturing precision
If precuring step is combined with curing step, then insert fixation is improved, but mechanical properties of cured material may be altered different from rest lens bulk material and shape of final lens may be altered
Solution Approach 1:
The patent merges the positioning and fixation functions into a single integrated precured insert assembly. The positioning features and fixation properties are combined in one component that is placed directly into the mold, eliminating the need for separate precuring and curing steps. This integration ensures uniform mechanical properties throughout the lens while maintaining secure insert fixation
Solution Approach 2:
The patent controls the curing parameters by using a single curing step instead of multiple sequential steps. By adjusting the curing time and conditions to ensure complete polymerization of the entire lens matrix including the insert assembly, the patent achieves uniform mechanical properties throughout the lens while maintaining secure fixation of the insert
3Manufacturing precision
If positioning guides (posts) are used, then insert positioning is improved, but device complexity increases
Solution Approach 1:
The patent extracts and removes the positioning guides (posts) from the mold structure. By eliminating these separate positioning components, the mold structure is simplified while still achieving precise insert positioning through the integrated positioning features of the precured insert assembly
Solution Approach 2:
The patent makes the insert assembly multi-functional by integrating positioning features, fixation properties, and optical characteristics into a single component. This universal design eliminates the need for separate positioning guides and other auxiliary structures, thereby simplifying the overall device complexity while maintaining positioning precision
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 method achieves accurate and consistent positioning of inserts in hydrogel contact lenses, eliminating small holes and mechanical property alterations, facilitating mass production with improved lens geometry and reducing bioburden risks.
Implementation Method 1
The more viscous first lens-forming composition is used to hold the insert in place
Implementation Method 2
curing the first and second lens-forming compositions in the molding assembly to form an embedded hydrogel lens precursor
Data Source
AI summary
A method for producing embedded hydrogel contact lenses comprises at least the following steps: depositing a small drop of a viscous lens-forming composition in the center of a female lens mold half; placing a preformed insert on top of the small drop precisely in the center of the female lens mold half so that the insert is held by capillary forces due to the presence of a thin layer of the viscous lens-forming composition between the insert and the molding surface of the female lens mold half; dosing an amount of another less viscous lens-forming composition on top of the insert to immerse the insert in the female lens mold half; closing tightly a male lens mold half onto the top of the female lens mold half halves to form a molding assembly; curing both the lens-forming compositions in the molding assembly to form an embedded hydrogel lens precursor.