Systems and methods for corneal surface ablation to correct hyperopia

Abstract

Systems, methods and apparatus for performing selective ablation of a corneal surface of an eye to effect a desired corneal shape, particularly for correcting a hyperopic/astigmatic condition by laser sculpting the corneal surface to increase its curvature. In one aspect of the invention, a method includes the steps of directing a laser beam onto a corneal surface of an eye, and changing the corneal surface from an initial curvature having hyperopic and astigmatic optical properties to a subsequent curvature having correctively improved optical properties. Thus, the curvature of the anterior corneal surface is increased to correct hyperopia, while cylindrical volumetric sculpting of the corneal tissue is performed to correct the astigmatism. The hyperopic and astigmatic corrections are preferably performed by establishing an optical correction zone on the anterior corneal surface of the eye, and directing a laser beam through a variable aperture element designed to produce a rectangular ablation (i.e., cylindrical correction) on a portion of the optical correction zone. The laser beam is then displaced by selected amounts across the optical correction zone to produce a series of rectangular ablations on the correction zone that increases the curvature of the corneal surface to correct the hyperopic refractive error.