Embedded Hydrogel Contact Lens Molding With Guide-Free Inserts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing embedded hydrogel contact lenses with inserts face challenges in accurately positioning the inserts, leading to bioburden trapping due to holes formed by positioning guides, which are susceptible to protein and bioburden buildup.
Innovation Solution
The method involves using inserts with alignment features on their front surface that are rotationally symmetric and have a curvature greater than twice that of the molding surface, allowing precise central alignment in the female mold half, eliminating the need for positioning guides and minimizing contact area, thereby preventing hole formation and bioburden accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If positioning guides (posts) are used in molds to precisely position inserts, then manufacturing precision of insert positioning is improved, but small holes are formed in resultant lenses which are susceptible to bioburden trapping
Solution Approach 1:
The invention removes the positioning guides (posts) from the mold structure entirely. Instead of using traditional positioning guides that create holes, the patent employs alignment features directly on the insert itself (such as circumferential edges or specific geometric features) that mate with corresponding features on the mold surface. This extraction of the positioning guide from the mold eliminates the source of hole formation while maintaining positioning precision through the insert's own alignment features.
Solution Approach 2:
Rather than having the mold provide positioning through guides, the invention inverts the approach by having the insert provide its own positioning features. The insert includes alignment features such as circumferential edges or geometric structures that actively engage with the mold surface to achieve precise positioning. This inversion transfers the positioning function from the mold to the insert, eliminating the need for mold-based positioning guides that create harmful holes.
2Ease of manufacture
If conventional cast-molding process is used with positioning guides, then inserts can be embedded in lenses, but the process complexity increases due to the need for positioning guides and associated holes
Solution Approach 1:
The invention simplifies the mold structure by completely removing the positioning guides (posts) from the mold design. The mold surface is reduced to essential molding features only, without additional positioning elements. This extraction of unnecessary components reduces mold complexity while maintaining the ability to embed inserts through the insert's own alignment features.
Solution Approach 2:
The insert serves its own positioning function through integrated alignment features such as circumferential edges or geometric structures built into the insert itself. These self-contained alignment features eliminate the need for separate positioning guides in the mold, allowing the insert to position itself during the molding process. This self-service approach reduces overall system complexity while maintaining manufacturing ease.
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
This approach enables efficient and consistent production of embedded hydrogel contact lenses with accurately positioned inserts, free of delamination and bioburden, ensuring high-quality manufacturing without protein or bioburden buildup.
Implementation Method 1
curing the lens-forming composition in the molding assembly to form an embedded hydrogel lens precursor that comprise a bulk hydrogel material formed from the lens-forming composition
Implementation Method 2
During the lens hydration, the hydrogel contact lenses will absorb water and typically can swell significantly in size
Data Source
AI summary
The invention relates to a method for producing embedded hydrogel contact lenses each having an insert that comprises alignment features capable of capable of aligning the insert in depth and radial position in a female mold half during cast molding of an embedded hydrogel contact lens. The alignment features protrude from the front surface, are rotationally symmetric with respect to the central axis of the insert and independently have a shape having a curvature being greater than 2 folds of the curvature of the molding surface so as to minimize contacting area between the alignment features and the molding surface. The use of such an insert can simplify the process for producing embedded hydrogel contact lenses and enable the process to be implemented readily in an automatic production.