Method and apparatus for combined cylindrical and spherical eye corrections
First Claim
1. A system for changing the anterior surface the cornea of an eye from an initial spherical and cylindrical curvature having myopic and astigmatic optical properties to a subsequent curvature having correctively improved optical properties, the cornea having a surface and a stroma, the system comprising laser for generating a beam of ultraviolet radiation along a path, and a variable aperture device disposed in the path of said beam for exposing the surface of the cornea and permitting the ultraviolet laser radiation to pass through the variable aperture element to selectively ablate the exposed surface of the cornea by photodecomposition, with penetration into the stroma and simultaneous spherical and cylindrical volumetric sculpturing removal of corneal tissue during at least a portion of the selective ablation to such penetration depth and profile as to characterize the surface of the cornea with said subsequent curvature.
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Abstract
A method for performing concurrent spherical and cylindrical corrections to the corneal surface of the eye to reduce myopia and astigmatism. A laser beam irradiates the corneal surface via a variable diameter iris and a slot produced by a pair of translatable blades. The width of the slot and the diameter of the iris are varied as the laser is pulsed to produce a toric ablation of the corneal surface. Alternatively, the laser beam is passed through a succession of apertures in a tilted variable aperture element to produce toric ablation. The total number of laser pulses required to effect both types of correction is equal to the number required for the spherical correction alone, reducing the laser power and the procedure time. The toric ablation produces no steep end walls as with standard cylindrical ablation procedures, thereby eliminating hyperopic shift and minimizing flattening along the ablated cylinder axis.
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Citations
12 Claims
- 1. A system for changing the anterior surface the cornea of an eye from an initial spherical and cylindrical curvature having myopic and astigmatic optical properties to a subsequent curvature having correctively improved optical properties, the cornea having a surface and a stroma, the system comprising laser for generating a beam of ultraviolet radiation along a path, and a variable aperture device disposed in the path of said beam for exposing the surface of the cornea and permitting the ultraviolet laser radiation to pass through the variable aperture element to selectively ablate the exposed surface of the cornea by photodecomposition, with penetration into the stroma and simultaneous spherical and cylindrical volumetric sculpturing removal of corneal tissue during at least a portion of the selective ablation to such penetration depth and profile as to characterize the surface of the cornea with said subsequent curvature.
- 7. A method of changing the anterior surface of the cornea of an eye from an initial spherical and cylindrical curvature having myopic and astigmatic optical properties to a subsequent curvature having correctively improved optical properties, the cornea having a stroma, which method comprises exposing the anterior surface of the cornea and permitting ultraviolet laser radiation to pass through a variable aperture element to selectively ablate the exposed anterior surface of the cornea by photodecomposition, with penetration into the stroma and simultaneous spherical and cylindrical volumetric sculpting removal of corneal tissue during at least a portion of the selective ablation to such penetration depth and profile as to characterize the anterior surface of the cornea with said subsequent curvature.
Specification