# 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 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Soft Contact Lenses Were Invented Using Hydrogels](https://patentbrief.org/patent/us/3220960/soft-contact-lens-hydrogel) — This patent describes the chemical recipe for soft, water-absorbing plastic materials that form the basis of modern soft contact lenses. - [Preventing Protein Damage with Extra Methionine](https://patentbrief.org/patent/us/5272135/lipitor-atorvastatin) — This 1993 patent describes how adding extra methionine to protein-based medicines can prevent them from degrading, especially in liquid or semi-solid forms. - [How a Specific Eye Drop Formula Treats Glaucoma](https://patentbrief.org/patent/us/RE48183/trikafta-triple-combination) — A patent for a precise, low-concentration eye drop solution designed to lower eye pressure in patients with glaucoma or ocular hypertension. - [How Special Sugars Make Medicines Dissolve Better](https://patentbrief.org/patent/us/4727064/azt-zidovudine) — This patent describes how to make poorly water-soluble drugs dissolve and absorb better by mixing them with specially modified, non-crystalline sugar molecules called cyclodextrin derivatives. - [Sticky, Tiny Plastic Balls Made from Acrylates](https://patentbrief.org/patent/us/3691140/post-it-repositionable-adhesive) — This 1972 patent describes how to make tiny, sticky, and durable plastic balls (microspheres) using a specific mix of acrylate chemicals and a special water-based process.