How Polystyrene Sulfonate Helps Treat Dry Eye Symptoms
A 1975 patent for an eye drop solution that uses a specific polymer to lubricate and cushion the eye, especially for contact lens wearers.
Original patent title: “Polystyrene sulfonate containing opthalmic solutions”
A 1975 patent for an eye drop solution that uses a specific polymer to lubricate and cushion the eye, especially for contact lens wearers. Granted to Burton Parsons and Co Inc in 1976 with 9 claims and 37 forward citations.
Key facts
Coverage
What does this patent actually cover?
The patent describes an eye drop solution containing polystyrene sulfonate, a polymer with a high molecular weight between 75,000 and 10,000,000. This polymer acts as a synthetic mucus layer to lubricate and cushion the eye, which is particularly useful for people experiencing irritation from hard or gel-type contact lenses. The solution is formulated to be either acidic or buffered to a pH between 7.4 and 8.2 to remain compatible with human eye tissue. It can also include additional agents like cellulose derivatives or surfactants to improve the solution's performance as a wetting or cleaning agent.
The gap
What does this patent NOT cover?
- Does not cover eye solutions that do not contain a styrene sulfonate polymer.
- Does not cover solutions where the polymer molecular weight falls outside the 75,000 to 10,000,000 range.
- Does not cover treatments for eye conditions that do not benefit from a synthetic mucus layer or lubrication.
- Does not cover the manufacturing process of the contact lenses themselves.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The invention uses a high-molecular-weight polymer to mimic the natural lubricating properties of mucus, providing a cushioning effect that remains stable on the eye surface.
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
Lubricating eye drops for contact lens wearers
Artificial tear solutions
Ophthalmic drug delivery vehicles
Why it matters
The bigger picture
This patent addressed the growing discomfort associated with early hard and soft contact lenses in the 1970s. By creating a synthetic mucus layer, it provided a way to manage dry eye symptoms and lens-related trauma, influencing the development of modern artificial tear formulations.
Filed
May 1, 1975
Granted
October 19, 1976
Market context
Who's building on this
Companies in this space
Major pharmaceutical companies specializing in ophthalmology, such as Alcon and Bausch + Lomb, have continued to refine the use of polymers and buffers in eye care products. These companies build on the foundational concept of using viscosity-modifying agents to improve ocular comfort.
Market impact
This patent contributed to the commercial viability of early contact lenses by providing a necessary comfort solution. It helped establish the category of lubricating eye drops as an essential companion product for the growing contact lens market in the late 20th century.
Claim 1 — Plain English
What this patent covers
The patent describes an eye drop solution containing polystyrene sulfonate, a polymer with a high molecular weight between 75,000 and 10,000,000. This polymer acts as a synthetic mucus layer to lubricate and cushion the eye, which is particularly useful for people experiencing irritation from hard or gel-type contact lenses. The solution is formulated to be either acidic or buffered to a pH between 7.4 and 8.2 to remain compatible with human eye tissue. It can also include additional agents like cellulose derivatives or surfactants to improve the solution's performance as a wetting or cleaning agent.
The clever bit
The invention uses a high-molecular-weight polymer to mimic the natural lubricating properties of mucus, providing a cushioning effect that remains stable on the eye surface.
What it does not cover
- Does not cover eye solutions that do not contain a styrene sulfonate polymer.
- Does not cover solutions where the polymer molecular weight falls outside the 75,000 to 10,000,000 range.
- Does not cover treatments for eye conditions that do not benefit from a synthetic mucus layer or lubrication.
- Does not cover the manufacturing process of the contact lenses themselves.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Early stage
Citation count
32/40
Moderately cited
Claim breadth
6/20
Moderate scope
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
$27K – $86K
Midpoint $54K · expired or expiring · industry ×2.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
9 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Rankin, B. F. (1976). How Polystyrene Sulfonate Helps Treat Dry Eye Symptoms (U.S. Patent No. 3,987,163). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/3987163/indomethacin
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Polystyrene Sulfonate Helps Treat Dry Eye Symptoms cover?
A 1975 patent for an eye drop solution that uses a specific polymer to lubricate and cushion the eye, especially for contact lens wearers.
Who owns patent US 3987163?
Burton Parsons and Co Inc owns this patent, granted in 1976.
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 3987163 cited by?
This patent has been cited by 37 later patents that build on its ideas.
What problem does this patent solve?
This patent addressed the growing discomfort associated with early hard and soft contact lenses in the 1970s. By creating a synthetic mucus layer, it provided a way to manage dry eye symptoms and lens-related trauma, influencing the development of modern artificial tear formulations.
What does this patent NOT cover?
Does not cover eye solutions that do not contain a styrene sulfonate polymer.
Patent monitoring