You can freely build on How Soft Contact Lenses Were Invented Using Hydrogels
This patent expired in 1982. Every claim — 1 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
Individual
Patent granted
1965
Expired
1982
Forward citations
228
What this patent covers
The patent defines a shaped body made from a hydrogel, which is a material that holds a large amount of water. It uses a base of a water-soluble monoester (like hydroxyethyl methacrylate) mixed with a small amount of a diester to create a cross-linked structure. This cross-linking acts like a microscopic net that holds the water inside the polymer without the material dissolving. By adjusting the ratio of these ingredients, the resulting plastic remains soft and flexible while retaining its shape in an aqueous environment.
What is now free to use
All 1 claims of US 3220960 are in the public domain. Specifically:
Claim 1: A SHAPED BODY ESSENTIALLY — 1 specific element
The 0 dependent claims add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
Does not cover rigid gas-permeable contact lenses made from non-hydrogel materials.
Does not cover non-cross-linked polymers that would simply dissolve in water.
Does not cover the specific manufacturing process of spinning or molding the lenses, only the chemical composition of the material itself.
Who is building on this today
Major global manufacturers like Alcon, Bausch + Lomb, and CooperVision continue to refine the chemical formulations of soft contact lenses based on the foundational principles of cross-linked hydrophilic polymers established here.
Products built on expired version of this technology
Soft contact lenses
Hydrogel wound dressings
Drug delivery implants
How to cite this patent in your documentation
Individual. US Patent 3220960. Cross-linked hydrophilic polymers and articles made therefrom. Granted 1965, expired 1982. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.