Multizone versus monozone in the treatment of high and moderate myopia with an excimer laser.

BACKGROUND AND OBJECTIVE: Numerous modifications have been proposed to photorefractive keratectomy (PRK) in the treatment of myopia in excess of 6.00 diopters (D). One of the techniques employed in an attempt to achieve better refractive results and to avoid, above all, the appearance of an intense haze, is the technique known as multizone. PATIENTS AND METHODS: We have attempted, in a prospective study, to compare the refractive results and the complications of monozone and multizone techniques for the treatment of moderate and high myopia. We performed 139 monozone PRKs and 30 multizone PRKs with a one-year follow-up. RESULTS: We did not find statistically significant differences between the two groups either in the degree of correction obtained nor in the final visual acuity. A statistically significant difference was found only in the number of cases with severe haze (greater than 3) which proved more frequent in the monozone group. CONCLUSION: Our results suggest the techniques are comparable in predictability and effectiveness. However, the incidence of severe haze was lower in the multizone group, which may render its use preferable in the treatment of myopias in excess of 6.00 D.