Photorefractive keratectomy to correct astigmatism with myopia or hyperopia.

Excimer laser photorefractive keratectomy as a means to flatten the central cornea has generated considerable interest. With this technique radial symmetric ablations can be performed to correct myopic refractive errors and excise superficial corneal pathology. We developed a technique that uses toric ablation to correct astigmatism. A new mask was designed for the MEL 60 Aesculap-Meditec excimer laser. The mask can be rotated regularly over 360 degrees. By varying the angular distances, the surgeon can increase ablation depth in any desired meridian. As a result, both cylindrical and spherical errors can be corrected in one procedure. Seventy-three eyes with either simple, myopic, mixed, or irregular astigmatism were treated. In each category of astigmatism, the surgery reduced the spherical component as well as the overall mean preoperative cylindrical refraction. Our findings suggest that this technique is a safe and effective procedure for correcting different types of astigmatism.