Direct Polyionic Coating of Silicone Hydrogel Contact Lenses
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Solution Overview
Problem
Current methods for coating ophthalmic lenses, particularly contact lenses, require multiple handling steps and significant manufacturing time due to layer-by-layer deposition techniques, which is inefficient and cumbersome.
Innovation Solution
A method involving the direct coating of contact lenses in their primary package using a polyionic coating solution with a specific molar charge ratio and pH range, where a first and second polyionic solution are applied sequentially, followed by sealing and maintaining the lens in an ophthalmically compatible storage solution until use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If layer-by-layer polyionic deposition technique is used to coat contact lenses, then surface properties can be altered to improve hydrophilicity and comfort, but manufacturing time and handling steps increase significantly
Solution Approach 1:
The patent combines multiple polyionic deposition steps into a single simultaneous treatment step. Instead of sequentially dipping the lens into multiple polyionic solutions as in conventional layer-by-layer techniques, the invention applies both polycationic and polyanionic materials together in one step, merging several operations into a single efficient process that maintains coating effectiveness while reducing manufacturing time
Solution Approach 2:
The patent performs preliminary conditioning of the contact lens surface before coating by treating it with a polyionic conditioning solution. This preliminary action prepares the surface to readily accept the polyionic coating materials in the subsequent single-step deposition, ensuring proper adhesion and uniform coating formation without requiring multiple sequential dipping steps
2Manufacturing precision
If multiple handling steps including preconditioning, dipping, and rinsing are performed, then coating quality can be maintained, but process complexity and handling time increase
Solution Approach 1:
The patent merges preconditioning, coating deposition, and rinsing operations into a single integrated treatment step. The contact lens is placed in a container containing both polyionic coating materials simultaneously, eliminating the need for sequential dipping and multiple rinsing steps between layers, thereby simplifying the overall process while maintaining coating quality
Solution Approach 2:
The patent employs a polyionic conditioning solution that automatically prepares the lens surface for coating. The conditioning solution self-adjusts to optimize surface properties, and the polyionic materials self-assemble on the lens surface through electrostatic interactions, reducing the need for complex controlled handling steps
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 reduces manufacturing time and handling steps while ensuring the coated lenses remain ophthalmically compatible, enhancing surface properties and comfort by altering hydrophilic or hydrophobic nature without the need for extensive processing.
Implementation Method 1
forming a coating on the contact lens by contacting the contact lens in the primary package with the first polyionic coating solution and adding the second polyionic coating solution to the first polyionic coating solution, wherein the coating comprises the negatively charged material and the positively charged material
Implementation Method 2
polyelectrolytes are suitable for surface precipitation from the solution, i.e. for forming layers or coatings on a surface
Data Source
Figure 1(A)~1(C)
Figure 2(A)~2(E)
AI summary
The present invention generally relates to a method for coating ophthalmic lenses, preferably contact lenses, more preferably silicone hydrogel contact lenses. In particular, the present invention is directed to a method for forming a coating comprising a polyionic material on a contact lens, preferably a silicone hydrogel contact lens, directly in the primary package and maintaining the coated contact lens within said primary package until insertion of the coated contact lens in the eye of the contact lens user. Before sealing the primary package, a tablet for adjusting the pH in the primary package is added.