Ophthalmic surgery method using non-contact scanning laser

Abstract

A refractive laser surgery process is disclosed for using compact, low-cost ophthalmic laser systems which have computer-controlled scanning with a non-contact delivery device for both photo-ablation and photo-coagulation in corneal reshaping. The basic laser systems may include flash-lamp and diode pumped UV solid state lasers (193-215 nm), compact excimer laser (193 nm), free-running Er:glass (1.54 microns), Ho:YAG (2.1 microns), Q-switched Er:YAG (2.94 microns), and tunable IR lasers, (750-1100) nm and (2.5-3.2) microns. The advantages of the non-contact, scanning device used in the process over other prior art lasers include being safer, reduced cost, more compact and more precise and with greater flexibility. The theory of beam overlap and of ablation rate and coagulation patterns is also disclosed for system parameters. Lasers are selected with energy of (0.01-10) mJ, repetition rate of (1-10,000), pulse duration of 0.01 nanoseconds to a few hundreds of microseconds, and with spot size of (0.05-2) mm for use with refractive laser surgery.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates to laser ophthalmic surgery using a compact, low-cost, low-power laser system with a computer-controlled, non-contact process and corneal topography to perform corneal reshaping using either surface ablation or thermal coagulation.2. Prior ArtVarious lasers have been used for ophthalmic applications including the treatments of glaucoma, cataract and refractive surgery. For non-refractive treatments (glaucoma and cataract), suitable laser wavelengths are in the ranges of visible to near infrared. They include: Nd:YAG (1064 nm), doubled-YAG (532 nm), argon (488, 514 nm), krypton (568, 647 nm), semiconductor lasers (630-690 nm and 780-860 nm) and tunable dye lasers (577-630 nm). For refractive surgeries (or corneal reshaping), ultraviolet (UV) lasers (excimer at 193 nm and fifth-harmonic of Nd:YAG at 213 nm) have been used for large area surface corneal ablation in a process called photorefractive keratec...

AI Technical Summary

Benefits of technology

The preferred embodiments of the basic ophthalmic surgery method uses a laser system for the ophthalmic surgery process, including: (1) a diode-pumped solid-state lasers of Nd:YAG or Nd:YLF which is frequency-converted by non-linear crystals of KTP (potassium titanyl phosphate), LBO (lithium triborate), KNbO3 (potassium niobate) and BBO (beta barium borate) into the fifth-harmonic at wavelength of 213 nm or 210 nm with energy of 0.01 to 5.0 mJ; (2) a compact, low-cost, low-power (energy of 1 to 10 mJ per pulse) argon fluoride excimer laser at 193 nm; (3) a frequency-converted Alexandite or Li:SAF or diode, lasers at (193-220) nm; (4) a compact, low-cost, Q-switched Er:YAG laser at 2.94 microns; (5) a free-running Ho:YAG (at 2.1 microns) or Er:glass (at 1.54 microns) or diode laser (1.9-2.5 microns); (6) ultrashort pulse IR laser (750-1100 nm) and (7) mid-IR (2.5-3.2 microns) laser generated from optical parametric oscillation.

In yet another aspect of the present invention, the above-described laser system provides an effective, low-cost tool for procedures of synthetic epikeratoplasty (SEK), where the artificial lens is sculpted with the laser to optimize lens curvature without causing problems of corneal haze and corrective regression. Real corneal tissues may also be sculpted and implanted by the above-described laser systems, a procedure known as laser myopic keratomileusis (MKM). Furthermore the UV and IR lasers disclosed in the present invention provide an effective tool for phototherapeutic keratectomy (PTK) which is currently conducted by high-power excimer lasers and the procedure conducted by diamond-knife called radial keratotomy (RK). This procedure conducted by UV or IR lasers is called laser radial keratotomy (LRK). The fundamental beam at 1064 or 1053 nm wavelength of the present invention may also be used for the intrastroma photorefractive keratectomy (IPK), where the laser beam is focused into the intrastroma area of the corneal and collagen tissue are disrupted.

Problems solved by technology

Beam steering and scanning is very difficult for these high-power, heavyweight excimer lasers.

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