How Soft Contact Lenses Were Invented Using Hydrogels
This patent describes the chemical recipe for soft, water-absorbing plastic materials that form the basis of modern soft contact lenses.
Original patent title: “Cross-linked hydrophilic polymers and articles made therefrom”
This patent describes the chemical recipe for soft, water-absorbing plastic materials that form the basis of modern soft contact lenses. Granted to Individual in 1965 with 2 claims and 228 forward citations, and it is now in the public domain.
Coverage
What does this patent actually cover?
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.
The gap
What does this patent NOT cover?
- 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.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The inventors realized that by adding just a 'minor amount' of a cross-linking diester to a hydrophilic polymer, they could create a stable, water-swollen solid that wouldn't wash away, effectively trapping water within a plastic matrix.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Soft contact lenses
Hydrogel wound dressings
Drug delivery implants
Why it matters
The bigger picture
This invention transformed vision correction by replacing hard, uncomfortable plastic lenses with soft, breathable alternatives. It is the foundational technology for the entire soft contact lens industry, which serves millions of people worldwide.
Filed
December 21, 1960
Granted
November 30, 1965
Market context
Who's building on this
Companies in this space
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.
Market impact
This patent enabled the creation of the soft contact lens market, shifting the industry away from rigid materials and creating a multi-billion dollar sector for daily and extended-wear vision correction products.
Claim 1 — Plain English
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.
The clever bit
The inventors realized that by adding just a 'minor amount' of a cross-linking diester to a hydrophilic polymer, they could create a stable, water-swollen solid that wouldn't wash away, effectively trapping water within a plastic matrix.
What it does not cover
- 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.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
This patent is in the public domain
See the Freedom to Build guide — what is free to use, what is not, and how to cite this patent.
PatentBrief Score
Impact Score
Moderate
Citation count
40/40
Highly cited
Claim breadth
1/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$48K – $154K
Midpoint $96K · expired or expiring · industry ×1.6
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Patent Claims
1 independent claim · 0 dependent
Claims are the legal boundaries of the patent. An independent claim stands alone. A dependent claim adds limitations to its parent, narrowing — but not broadening — the scope.
The original legal language
Original claims
2 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Drahoslav, L., & Otto, W. (1965). How Soft Contact Lenses Were Invented Using Hydrogels (U.S. Patent No. 3,220,960). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/3220960/soft-contact-lens-hydrogel
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
Embed
Add this patent to your site
Drop this plain-English patent card into any blog post or article — free, no signup. It always links back to the full breakdown here.
<div data-patentlens-widget data-patent-number="US3220960"></div> <script src="https://patentbrief.org/embed.js" async></script>
Stay in the loop
Get a weekly digest of new patents.
One email per week. No spam. Unsubscribe anytime.
Keep exploring
Related patents you should know
US 4683195 · 1987
How to Make Billions of Copies of a DNA Segment
This patent describes the Polymerase Chain Reaction (PCR), a method to rapidly create many copies of a specific piece of DNA or RNA, enabling its detection and analysis.
Cetus Corp
US 8697359 · 2014
How to Edit Genes in Human Cells Using an Engineered CRISPR System
This patent describes an engineered CRISPR-Cas9 system for precisely cutting DNA in eukaryotic cells to change how genes work, opening the door for gene editing in complex organisms.
Massachusetts Institute of Technology
US 7657849 · 2010
How the iPhone's Slide-to-Unlock Gesture Works
Apple's 2010 patent describes unlocking a device by dragging a specific graphical image across the touchscreen along a predefined path, a gesture that became iconic with the original iPhone.
Apple Inc
US 4733665 · 1988
How Doctors Implant a Permanent Stent Using a Balloon
This patent describes the method for placing a permanent, expandable wire mesh tube inside a blood vessel or other body tube using a balloon-tipped catheter to widen it and keep it open.
Expandable Grafts Partnership
US 4965188 · 1990
How to Make Many Copies of a DNA Piece with Heat
This patent describes the Polymerase Chain Reaction (PCR) method, a technique to make millions of copies of a specific DNA segment using a heat-resistant enzyme and repeated temperature changes.
Cetus Corp
US 4235871 · 1980
How to Encapsulate Active Materials in Lipid Bubbles Efficiently
This patent describes a method for trapping biologically active substances inside tiny, multi-layered fat bubbles called liposomes, using a specific water-in-oil emulsion and gel-forming process to improve how much material gets captured.
Individual
Semantically similar
You might also find these interesting
US 3691140 · 1972
Sticky, Tiny Plastic Balls Made from Acrylates
US 3167440 · 1965 · Rainbow Crafts Inc
How Play-Doh Was Invented
US 3322485 · 1967 · RCA Corp
How Liquid Crystal Displays (LCDs) Were Invented
US 4727064 · 1988 · US Department of Health and Human Services
How Special Sugars Make Medicines Dissolve Better
More to explore
More in Biotech & Medicine
US 4683195 · 1987 · Cetus Corp
How to Make Billions of Copies of a DNA Segment
US 8697359 · 2014 · Massachusetts Institute of Technology
How to Edit Genes in Human Cells Using an Engineered CRISPR System
US 4733665 · 1988 · Expandable Grafts Partnership
How Doctors Implant a Permanent Stent Using a Balloon
US 4965188 · 1990 · Cetus Corp
How to Make Many Copies of a DNA Piece with Heat
New to patents?
Common Questions
Frequently Asked Questions
What does How Soft Contact Lenses Were Invented Using Hydrogels cover?
This patent describes the chemical recipe for soft, water-absorbing plastic materials that form the basis of modern soft contact lenses.
Who owns patent US 3220960?
Individual owns this patent, granted in 1965.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 3220960 cited by?
This patent has been cited by 228 later patents that build on its ideas.
What problem does this patent solve?
This invention transformed vision correction by replacing hard, uncomfortable plastic lenses with soft, breathable alternatives. It is the foundational technology for the entire soft contact lens industry, which serves millions of people worldwide.
What does this patent NOT cover?
Does not cover rigid gas-permeable contact lenses made from non-hydrogel materials.
Same assignee
More from Individual
Patent monitoring