Abstract: A cornea is altered in shape by providing a template body to guide a surgical blade, the body being formed in a semi-spherical hollow with the outer wall concentric with the inner surface of the cornea and the inner wall of the template body concentric with the outer surface of the cornea. The template body affords a rest surface for a shoulder on the surgical blade to limit penetration of the blade into the cornea in accordance with the thickness of the template body, which varies inversely with the thickness of the cornea to preclude blade penetration of the anterior chamber of the eye behind the cornea. Guide slits in various patterns are formed in the template body between the optic zone and the limbus circles diameter of the eye to change the resistance of the cornea to inner eye pressures and thus alter the corneal shape to correct focal problems of the eye.