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Abstract

An argon-flouride excimer laser or other laser source capable of generating far-ultraviolet radiation at 193 nm is pulsed with energy densities of greater than 20 mj per cm.sup.2 at a repetition rate up to 25 pulses per second to direct its radiation through a mask and onto corneal tissue, or other biological matter, to form a groove therein of predetermined configuration and depth by a process of ablative photodecomposition. The masks are formed with a slit, circular, crescent or other openings of widths between 30 and 800 microns, and may even be formed to provide a graded intensity center to edge. The mask is reflective or composed of or faced with an organic polymer to prevent heat build-up. Each micron of the depth of a 200 micron deep groove formed in corneal tissue, for example, resulted from the application of 1 joule per square centimeter of radiation, from a series of pulses delivered at intensities of between 100 mj and 200 mj per square centimeter and at a laser pulse rate of between 1 and 25 Hertz; the entire groove taking 100 seconds.

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First Claim