EXCIMER-LASER PHOTOREFRACTIVE KERATECTOMY WITH TAPERED TRANSITION ZONE FOR HIGH MYOPIA - A PRELIMINARY-REPORT OF 6 CASES

To improve the stability of refraction after photorefractive keratecto my (PRK) to correct myopia, we developed a new ablation profile with a 1.5 mm wide tapered transition zone bordering the refractive zone. Th e treated area's total diameter was 7 mm, the diameter of the refracti ve zone, 4 mm. The effect of the tapered transition zone on refraction stability was investigated in a 12-month follow-up study of six eyes of six patients. All eyes were partially sighted, with corresponding f undus changes and myopia of between -12.0 diopters (D) and -24.0 D. Th e therapeutic goal was to reduce myopia by 10.0 D to 13.0 D. All patie nts were treated unilaterally. The change in refraction in five eyes 1 2 months after surgery was less-than-or-equal-to 1.0 D as compared wit h the first month postoperatively. In one case the change after 12 mon ths was 2.75 D. There was less regression after PRK with the transitio n zone than with a conventional ablation profile (i.e., stability was improved). However, epithelial healing took longer.