Sculpture apparatus for correcting curvature of the cornea.

摘要

In the context of ultraviolet-laser sculpting of the cornea to achieve optical correction through a newly shaped anterior surface, the invention subjects the laser beam to certain shaping and homogenizing operations prior to any attempt to specially characterize the beam for a particular sculpture procedure. In a preferred embodiment, an excimer laser (11) produces a beam of rectangular section, and the short dimension of this section is optically expanded (50, 51) to produce a beam section having quadrature profiles of substantially equal extent on opposite sides of the central axis of the expanded beam; the expanded beam is thereafter subjected to optical rotation (52) in the course of a given surgical exposure to the cornea, whereby irregularity in the intensity profile of the expanded beam is converted to an irregularity of rotational symmetry. A compensating filter (55) having an attenuating profile of rotational symmetry effectively offsets irregularity of circular symmetry in the time-integrated product of beam rotation.