# How Lasers Correct Vision by Reshaping the Eye's Front Surface > This patent describes a method for precisely reshaping the front surface of the eye using an ultraviolet laser to correct vision problems like nearsightedness, farsightedness, and astigmatism. - **Patent:** US 4665913 - **Original title:** Method for ophthalmological surgery - **Owner:** LRI LP - **Granted:** 1987 - **Status:** Public domain (expired) - **Times cited:** 381 - **Field:** medical_devices, biotech, healthcare, lasers, ophthalmology ## What it does The patent details a method for changing the optical properties of an eye by operating solely on the cornea's anterior surface. It uses selective ultraviolet (UV) laser radiation to remove corneal tissue through a process called ablative photodecomposition (Claim 1). This process sculpts the cornea to a predetermined curvature profile, correcting vision defects. For example, to fix astigmatism, the laser beam is focused to a tiny spot and scanned over the cornea in a specific pattern, removing tissue to a precise depth (Claim 3). This scanning action changes the cornea's shape, allowing it to focus light correctly. ## What it does NOT cover - Does not cover vision correction methods that operate on parts of the eye other than the anterior surface of the cornea. - Does not cover laser eye surgery using non-ultraviolet light, as it specifically claims "ultraviolet irradiation" (Claim 1). - Does not cover methods that reshape the cornea without removing tissue through "ablative photodecomposition" (Claim 1). - Does not cover techniques that do not aim for a "predetermined curvature profile" to correct specific vision errors (Claim 1). - Does not cover procedures where the laser ablation does not penetrate into the stroma layer of the cornea (Claim 1). ## The clever bit The truly clever part was realizing that ultraviolet lasers could precisely remove corneal tissue layer by layer without causing heat damage to surrounding cells, a process called ablative photodecomposition. This allowed for the exact sculpturing of the cornea's surface to a predetermined shape, something previous surgical methods could not achieve with such control. ## Real-world examples 1. Photorefractive Keratectomy (PRK) 2. Laser-Assisted Subepithelial Keratomileusis (LASEK) 3. Epi-LASIK 4. Early forms of LASIK procedures ## Why it matters This patent is foundational for modern laser eye surgery, specifically procedures like Photorefractive Keratectomy (PRK). It introduced the precise use of UV lasers to sculpt the cornea, moving beyond less accurate surgical methods. This technology made it possible to correct common vision problems like nearsightedness, farsightedness, and astigmatism with high precision, significantly reducing reliance on glasses and contact lenses for millions of people. ## Frequently asked questions ### What does How Lasers Correct Vision by Reshaping the Eye's Front Surface cover? This patent describes a method for precisely reshaping the front surface of the eye using an ultraviolet laser to correct vision problems like nearsightedness, farsightedness, and astigmatism. ### Who owns patent US 4665913? LRI LP owns this patent, granted in 1987. ### 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 4665913 cited by? This patent has been cited by 381 later patents that build on its ideas. ### What problem does this patent solve? This patent is foundational for modern laser eye surgery, specifically procedures like Photorefractive Keratectomy (PRK). It introduced the precise use of UV lasers to sculpt the cornea, moving beyond less accurate surgical methods. This technology made it possible to correct common vision problems like nearsightedness, farsightedness, and astigmatism with high precision, significantly reducing reliance on glasses and contact lenses for millions of people. ### What does this patent NOT cover? Does not cover vision correction methods that operate on parts of the eye other than the anterior surface of the cornea. **Full plain-English explainer:** https://patentbrief.org/patent/us/4665913/laser-eye-surgery-lesperance **Original patent:** https://patents.google.com/patent/US4665913 --- _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: - [Adjusting Eye Implants with Lasers for Clearer Vision](https://patentbrief.org/patent/us/12734028/systems-and-methods-for-spectacle-independence-using-refractive-index-writing) — This patent describes using precise laser pulses to change the focusing power of an implanted artificial eye lens, helping people see clearly without glasses. - [A Medical Device for Puncturing Tissue with an Energy-Delivering Tip](https://patentbrief.org/patent/us/12733955/methods-and-devices-for-puncturing-tissue) — This patent describes a medical device designed to puncture tissue using an energy-delivering tip, featuring a specific shape with curved and straight sections and a constant diameter layer for precise control. - [How Multi-Electrode Systems Precisely Control Tissue Heating for Ablation](https://patentbrief.org/patent/us/12733969/ablation-system-methods-and-controllers) — This patent describes a method for starting a medical ablation procedure using multiple electrodes, carefully controlling the temperature and how fast it rises at each electrode to safely treat tissue. - [How Polystyrene Sulfonate Helps Treat Dry Eye Symptoms](https://patentbrief.org/patent/us/3987163/indomethacin) — A 1975 patent for an eye drop solution that uses a specific polymer to lubricate and cushion the eye, especially for contact lens wearers. - [Seeing Blood Flow Deep Inside Tissue Without Touching It](https://patentbrief.org/patent/us/9861319/noncontact-three-dimensional-diffuse-optical-imaging-of-deep-tissue-blood-flow-d) — This patent describes a way to create 3D images of blood flow up to 1.5 cm deep inside body tissue using near-infrared light, all without any physical contact with the skin.