Ophthalmic surgery method using non-contact scanning laser

a scanning laser and laser technology, applied in the field of laser ophthalmic surgery, can solve the problems of difficult beam steering and scanning of high-power, heavy-weight excimer lasers, and achieve the effect of low-power

Inactive Publication Date: 2002-01-08
LASERSIGHT TECH
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  • Application Information

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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...

Problems solved by technology

Beam steering and scanning is very difficult...

Method used

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Embodiment Construction

The theoretical background of the present invention with regards to the beam overlap and ablation rate in photorefractive keratectomy, intrastroma photokeratectomy, synthetic epikeratoplasty, phototherapeutic keratectomy and myopic keratomileusis procedures described in the present invention is as follows.

Given a laser energy per pulse of m (in mJ), an intensity of I (in mJ / cm.sup.2) may be achieved by focusing the beam into an area of A, where I=E / A. For corneal tissue ablation to occur requires the laser intensity (I) to be above the photoablation threshold (PAT), (60-120) mJ / cm.sup.2 for UV-laser (193-215 nm) and (200-600) mJ / cm.sup.2 for IR-laser (2.5-3.2 microns). Therefore it is always possible to tightly focus a laser beam and achieve the PAT value even for a low-energy laser (0.1-5) mJ. The drawback of using a low-energy, small-spot laser for large area ablation is that the operation time will be longer than that of a large-spot but high-power laser. However, time of operati...

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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...

Claims

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Application Information

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IPC IPC(8): A61F9/01A61F9/007
CPCA61B18/203A61F9/008A61F9/00804A61F9/00821A61F2009/00853A61F2009/00872A61F2009/00882A61F2009/00897A61B2018/20359B23K26/0622B23K26/361B23K2103/32B23K2103/50
Inventor LIN, J. T.
Owner LASERSIGHT TECH
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