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.

What it 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.

What it doesn't 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.

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.

Real-world examples

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