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Abstract

A method and system are described for performing photorefractive keratectomy procedure employing pulses of photoablative radiation to selectively ablate corneal tissue of a patient's eye in an ablation zone on the anterior corneal surface to produce a desired refractive correction in the corneal tissue. The method and system employ control of the effect of ocular fluid at the corneal surface so as to reduce the disturbance of such fluid on the desired ablation process while maintaining hydration of the corneal tissue. Controlling the average repetition rate of the radiation pulses applied to the corneal surface so as to reduce intrapulse fluid accumulation at the corneal surface without dehydrating the corneal tissue, selecting an increased fluence level of the pulse applied to the corneal surface to reduce the effect of fluid accumulation at the corneal surface, and applying evaporative energy to the site of incidence of a pulse of an ablative beam prior to incidence of said pulse at said site are shown as ways to effect this control. Application of the new method and system to wide area ablation techniques and to scanning techniques are described Reduction of irregularities when ablating large areas, e.g., grater than 5.5 cm is made possible in either case.

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