Hybrid Contact Lens Bonding via Segmented Polymerization
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Solution Overview
Problem
Existing manufacturing processes for hybrid contact lenses face challenges such as unsatisfactory and non-adjustable lenses due to difficulties in polymerizing hydrophilic materials with nonhydrophilic materials, and the need for molds limits lens size and increases costs.
Innovation Solution
The process involves gluing pre-existing, already polymerized oxygen-permeable rigid and hydrophilic flexible disks after hydration of the flexible disk, followed by drying and machining to create a hybrid lens with a release band, allowing for adjustable and cost-effective production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrophilic flexible portion is polymerized in the presence of nonhydrophilic rigid portion, then connection between the two parts is achieved, but polymerization is difficult and lens quality is unsatisfactory
Solution Approach 1:
The lens manufacturing process is divided into separate stages: first the rigid portion is formed, then removed, and finally the flexible portion is polymerized in its absence. This segmentation allows each portion to be optimized independently without the polymerization difficulties that arise when attempting to polymerize hydrophilic materials in the presence of nonhydrophilic materials.
Solution Approach 2:
The rigid portion is pre-formed and then temporarily removed before polymerizing the flexible portion. This preliminary action of removing the rigid portion enables the flexible portion to be polymerized under optimal conditions without interference from the nonhydrophilic material, and the rigid portion is later reattached through adhesives or mechanical retention.
2Ease of manufacture
If molds are used for manufacturing hybrid lenses, then polymerization can be achieved, but lens size is limited and costs increase
Solution Approach 1:
The manufacturing process separates the formation of the rigid and flexible portions into independent steps, eliminating the need for complex multi-component molds. The rigid portion can be manufactured separately using conventional techniques, then the flexible portion is polymerized separately and assembled, allowing greater flexibility in lens sizing and design variations without requiring custom molds for each configuration.
Solution Approach 2:
By removing the rigid portion before polymerizing the flexible portion, the process allows for parameter changes in lens size and design without being constrained by mold limitations. Different sized flexible portions can be polymerized using the same general process, and the rigid portion can be selected or customized to match, providing greater adaptability and reducing the need for multiple specialized molds.
3Ease of operation
If flexible portion changes volume upon hydration after gluing, then lens becomes functional, but warping and stress occur at the bonding site
Solution Approach 1:
The rigid portion is pre-formed with a geometry that anticipates the volume change of the flexible portion upon hydration. By removing the rigid portion before flexible portion polymerization, the design can accommodate for the expected swelling of the hydrophilic material, allowing the bonding interface to be positioned or shaped in advance to compensate for future volume changes and minimize warping and stress.
Solution Approach 2:
The design accounts for parameter changes in the flexible portion by allowing it to be polymerized in a dry state with different dimensional characteristics, then accommodating its expansion upon hydration. The bonding interface is designed to handle the transition from dry to hydrated state, with the rigid portion geometry adjusted to maintain stability despite the volume change of the flexible portion.
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 method prevents warping and stress in the lens, enabling a final curved shape suitable for the eye and allows for easy removal, while minimizing costs and increasing adjustability.
Implementation Method 1
an adhesive material between said rigid disk and said flexible disk, forming a bonding layer
Implementation Method 2
the hydrophilic flexible portion changes its volume and surface area according to its degree of hydration
Implementation Method 3
said composite part is dried for a defined time sufficient to allow the dehydration of the flexible disk to a second defined level of hydration lower than the first
Data Source
AI summary
The present invention relates to a process and to a device for manufacturing a hybrid contact lens (7, 21), from a composite part formed of a rigid central portion connected to a soft peripheral portion (9, 23) by an adhesive material (10, 24), to such a part and to such a lens. Starting from an oxygen-permeable rigid disc (2) and from a previously hydrated hydrophilic soft disc (3), a composite part (1) comprising three superposed layers is formed by bonding one disc to the other, said composite part (1) is dried for a defined time sufficient to allow the dehydration of the soft disc, then said composite part is dry cut with a machining tool by presenting the face of the hydrophilic soft portion (3) toward the tool in order to obtain the hybrid lens, by making a release strip (26) on the outer circumference (27) of the rigid peripheral portion.