CLINICAL ANALYSIS OF EXCIMER-LASER PHOTOREFRACTIVE KERATECTOMY USING A MULTIPLE ZONE TECHNIQUE FOR SEVERE MYOPIA

PURPOSE: In an investigational procedure, excimer laser photorefractiv e keratectomy for severe myopia was performed at three clinical trial centers to determine the effectiveness of the multiple zone technique. METHODS: A VisX Model Twenty/Twenty excimer laser (VisX, Santa Clara, California) was used to perform photorefractive keratectomy on 14 sev erely myopic eyes (-10.37 to -24.5 diopters) of 12 patients by using a multiple zone technique. Postoperative follow-up ranged from six mont hs to two years; retreatments were performed on four patients, with a follow up of at least nine months. RESULTS: At six months postoperativ ely, before retreatment, three of the 14 eyes were within 2 diopters a nd seven of the 14 eyes were within 4 diopters of attempted correction . Regression of effect. to more severe myopia was worse in five eyes t reated with nitrogen gas blowing. Retreatments also demonstrated consi derable myopic regression. Three patients had loss of two or more line s of best corrected visual acuity, and these patients also had moderat e or severe levels of haze. CONCLUSION: Excimer laser photorefractive keratectomy for severe myopia using a multiple zone technique is assoc iated with considerable regression, haze, and loss of best corrected v isual acuity, especially when performed in association with nitrogen g as blowing.