Excimer laser photorefractive keratectomy with tapered transition zone for high myopia

To improve the stability of refraction after photorefractive keratectomy (PRK) to correct myopia, we developed a new ablation profile with a 1.5 mm wide tapered transition zone bordering the refractive zone. The treated area's total diameter was 7 mm, the diameter of the refractive 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 fundus changes and myopia of between -12.0 diopters (D) and -24.0 D. The therapeutic goal was to reduce myopia by 10.0 D to 13.0 D. All patients were treated unilaterally. The change in refraction in five eyes 12 months after surgery was < or = 1.0 D as compared with the first month postoperatively. In one case the change after 12 months was 2.75 D. There was less regression after PRK with the transition zone than with a conventional ablation profile (i.e., stability was improved). However, epithelial healing took longer.