Embedded Hydrogel Contact Lens Molding Method
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Solution Overview
Problem
Existing methods for producing embedded hydrogel contact lenses with rigid hydrophobic inserts face challenges such as lens distortion, delamination, and precise positioning of inserts during the hydration and handling of the lenses.
Innovation Solution
A method using a set of three mold halves to precisely position and embed rigid hydrophobic inserts within silicone hydrogel contact lenses, ensuring accurate placement and preventing delamination by merging the insert surfaces with the lens surfaces at a depth of less than 10 microns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid hydrophobic inserts are embedded in silicone hydrogel contact lenses, then vision correction and corneal health benefits are improved, but lens distortion and delamination occur during hydration and handling
Solution Approach 1:
The patent applies parameter changes by modifying the mechanical properties of the hydrogel matrix through controlled crosslinking density and composition. By adjusting the crosslinking degree and using specific crosslinking agents, the hydrogel's elastic modulus and water absorption characteristics are optimized to match the rigid insert, preventing delamination while maintaining vision correction effectiveness.
Solution Approach 2:
The patent employs composite materials by combining silicone hydrogel with rigid hydrophobic insert materials (such as PMMA or other rigid polymers). This composite structure allows the lens to benefit from both the oxygen permeability and comfort of hydrogel and the optical stability and astigmatism correction of rigid inserts, while addressing interfacial adhesion issues through surface treatment and mechanical property matching.
2Adaptability or versatility
If inserts are embedded in hydrogel contact lenses, then functional benefits are improved, but precise positioning of inserts becomes difficult
Solution Approach 1:
The patent applies preliminary action by pre-forming the rigid insert with specific geometric features (such as positioning protrusions or asymmetric shapes) before embedding it in the hydrogel matrix. The insert is prepared in advance with precise dimensions and surface treatments that ensure accurate positioning during the molding process, eliminating the need for complex real-time positioning mechanisms.
Solution Approach 2:
The patent uses an intermediary approach by incorporating positioning structures (such as guide pins, alignment features, or pre-formed cavities) in the mold that act as mediators to guide the insert into the correct position during embedding. These intermediary structures ensure precise positioning without requiring complex adjustment mechanisms during the manufacturing process.
3Ease of operation
If hydrogel contact lenses are hydrated, then wearing comfort is improved, but lens swelling and delamination occur
Solution Approach 1:
The patent applies parameter changes by controlling the hydrogel's water content, crosslinking density, and elastic modulus to match the mechanical properties of the rigid insert. By optimizing these parameters, the hydrogel's swelling behavior is regulated to minimize differential expansion between the hydrogel matrix and the rigid insert, thereby preventing delamination while maintaining the comfort benefits of hydration.
4Ease of manufacture
If conventional molding processes are used, then production simplicity is maintained, but embedded insert positioning and lens quality are compromised
Solution Approach 1:
The patent applies preliminary action by pre-forming the rigid insert with precise geometric features and surface treatments before embedding it in the hydrogel matrix during the molding process. This pre-preparation ensures that the insert is ready for accurate positioning and embedding without requiring complex post-processing steps, maintaining production simplicity while improving embedding 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 enables the production of embedded hydrogel contact lenses that are not susceptible to delamination, maintaining optical clarity and mechanical integrity even after autoclaving and storage.
Implementation Method 1
During the lens hydration, the hydrogel contact lenses will absorb water and typically can swell significantly in size
Implementation Method 2
ensuring accurate placement and preventing delamination by merging the insert surfaces with the lens surfaces at a depth of less than 10 microns
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for producing embedded hydrogel contact lenses involving a set of 3-mold halves consisting essentially of: one female lens mold half having a molding surface defining the anterior surface of a contact lens; one male lens mold half having a molding surface defining the posterior surface of the contact lens; and an insert mold half having a molding surface defining one of the front and back surfaces of an insert. One of the lens mold halves is used twice: first with the insert mold half for molding an insert during first curing process and then with the other lens mold half for molding an embedded hydrogel contact lens with the molded insert embedded partially or fully therein during second curing process. The invention also relates to embedded hydrogel contact lenses produced from a method of the invention.