# 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.

- **Patent:** US 3987163
- **Original title:** Polystyrene sulfonate containing opthalmic solutions
- **Owner:** Burton Parsons and Co Inc
- **Granted:** 1976
- **Status:** Public domain (expired)
- **Times cited:** 37
- **Field:** biotech, pharmaceutical

## What it does

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.

## 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.

## 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.

## Real-world examples

1. Lubricating eye drops for contact lens wearers
2. Artificial tear solutions
3. Ophthalmic drug delivery vehicles

## Why it matters

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.

## 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.

**Full plain-English explainer:** https://patentbrief.org/patent/us/3987163/indomethacin

**Original patent:** https://patents.google.com/patent/US3987163

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._