Refractive surgery and presbyopia correction using infrared and ultraviolet lasers

Abstract

A method and surgical technique for corneal reshaping and for presbyopia correction are provided. The preferred embodiments of the system consists of a scanner, a beam spot controller and coupling fibers and the basic laser having a wavelength of (190-310) nm, (0.5-3.2) microns and (5.6-6.2) microns and a pulse duration of about (10-150) nanoseconds, (10-500) microseconds and true continuous wave. New mid-infrared gas lasers are provided for the corneal reshaping procedures. Presbyopia is treated by a method which uses ablative laser to ablate the sclera tissue and increase the accommodation of the ciliary body. The tissue bleeding is prevented by a dual-beam system having ablative and coagulation lasers. The preferred embodiments include short pulse ablative lasers (pulse duration less than 200 microseconds) with wavelength range of (0.15-3.2) microns and the long pulse (longer than 200 microseconds) coagulative lasers at (0.5-10.6) microns. Compact diode lasers of (980-2100) nm and diode-pumped solid state laser at about 2.9 microns for radial ablation patterns on the sclera ciliary body of a cornea are also disclosed for presbyopia correction using the mechanism of sclera expansion.

Description

[0001]The questions raised in reexamination request 90 / 006,089, filed Aug. 21, 2001 have been considered and the results thereof are reflected in this reissue patent which constitutes the reexamination certificate required by 35 U.S.C. 307 as provided in 37 CFR 1.570(e), for ex parte reexaminations, or the reexamination certificate required by 35 U.S.C. 316 as provided in 37 CFR 1.997(e) for inter partes reexaminations.<?insert-end id="INS-S-00001" ?>BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to refractive surgical systems using low-power, infrared and ultraviolet lasers in a predetermined scanning patterns in procedures of photorefractive keratectomy (PRK), laser assisted in situ keratomileusis (LASIK) and laser sclera expansion (LASE), a new procedure for presbyopia correction.[0004]2. Prior Art[0005]Refractive surgeries (or corneal reshaping) including a procedure called photorefractive keratectomy (PRK) and a more recent p...

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Benefits of technology

[0025]We should also notice that the problems of central islands, caused by uneven hydration level and shock-wave on the corneal surface, would be mostly reduced by above-introduced VSS designs and controlling these beams scanning in a counter-directions. Moreover, it is another preferred aspect of the present invention to use a random predetermined scanning pattern such that the thermal effect, shock wave and uneven hydration level on the corneal surface can be minimized. The random scanning can be easily achieved by a software design based on the desired correction profiles which is governed by myopic diopter, ablation zone diameter and the position (coordinate) of each scanning beam on the corneal surface. The pre-calculated positions of each scanning spot can...

Problems solved by technology

Moreover, UV laser systems suffer problems such as optical damage of the coated mirrors, unstable and short lifetime of the lasing gases and high cost toxic gas of fluorine (for excimer laser).

Low beam delivery efficiency and complexity of beam uniformity are other drawbacks of UV refractive lasers.

At the present time, there is no any commercial or clinically practical mid-IR refractive laser system been developed based upon the prior arts because of the inherent problems and difficulties to be discussed as follows.

Development of Q-switched Er:YAG system was inherently limited by factors of optical damage of the Q-switching components, coating problems due to strong water absorption, and the low repetition rate Oess than 25 Hz) due to the cooling problems of the laser rod.

To overcome all these inherent drawbacks in an Er:YAG system will not be cost effective and a high maintenance efforts will be required when it is used for refractive surgery.

Another alternative proposed by Lin and Telfail et al., the OPO-laser also had technical difficulties in making a clinically practical system.

At this time only low repetition rate OPO-laser (lower than 30 Hz) at low energy (less than 5 mi per pulse) was tested due to the problems of: low conversion efficiency from near-IR to m...

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