Embedded Hydrogel Contact Lens Molding Without Positioning 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, leading to small holes that trap bioburden and compromise lens integrity.
Innovation Solution
A method involving multiple mold halves is employed to form embedded hydrogel contact lenses, eliminating the need for positioning guides, ensuring precise insert placement and avoiding small voids, with a process that includes curing and separating mold assemblies to create lenses with inserts sandwiched between hydrogel layers.
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 placement is improved, but small holes are formed in the resultant lenses which trap bioburden and compromise lens integrity
Solution Approach 1:
The invention removes the positioning guides (posts) from the mold structure entirely. Instead of using physical guides that leave holes, the method relies on the natural alignment and curing process of the hydrogel material to achieve precise insert positioning without compromising lens integrity through hole formation.
Solution Approach 2:
The insert is pre-positioned within the mold cavity before the hydrogel material is introduced and cured. This preliminary positioning ensures accurate placement without requiring posts or guides that would create harmful holes in the final lens product.
2Ease of manufacture
If conventional full cast-molding process is used to produce hydrogel contact lenses, then ease of manufacture is improved, but the process is complex and time-consuming with multiple steps including molding, demolding, extraction, hydration, packaging, and sterilizing
Solution Approach 1:
The invention combines multiple conventional manufacturing steps into a single integrated cast-molding process. The insert positioning, hydrogel material deposition, and lens formation are performed simultaneously in one molding operation, eliminating the need for separate demolding, extraction, and positioning steps while maintaining manufacturing simplicity.
3Adaptability or versatility
If inserts are embedded in hydrogel contact lenses for various purposes, then functionality and versatility of lenses are improved, but the process of precisely positioning and fixing inserts becomes challenging and complex
Solution Approach 1:
The hydrogel material itself serves the dual function of both the lens substrate and the positioning medium for the insert. As the hydrogel cures, it naturally conforms to and secures the insert in its intended position without requiring additional positioning mechanisms or complex fixation processes, thereby maintaining versatility while simplifying the embedding procedure.
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 produces lenses with inserts accurately positioned, free of bioburden-trapping voids, and maintains lens integrity, allowing for mass production in an automated line with improved wearing comfort and reduced delamination risk.
Implementation Method 1
curing the insert-forming composition in the first molding assembly to form a molded insert; curing the first lens-forming composition in the second molding assembly to form a lens precursor; curing the second lens-forming composition in the third molding assembly to form an embedded hydrogel contact lens
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 is directed to an embedded hydrogel contact lens, which comprises an insert sandwiched between two layers of hydrogel materials and can be produced according to a cast molding method including the procedures involving two females halves (FC1 and FC2) and two male halves (BC1 and BC2) and three consequential molding steps involving three molding assemblies: the 1st one formed between FC1 and BC1 for molding an insert; the 2nd one formed between FC1 and BC2 for molding a lens precursor having the molded insert embedded in a layer of a hydrogel material in a way that the front surface of the molded insert merges with the convex surface of the lens precursor; and the 3rd one formed between FC2 and BC2 for molding an embedded hydrogel contact of the invention.