FOR HOW LONG CAN REGRESSION CONTINUE AFTER PHOTOREFRACTIVE KERATECTOMY FOR MYOPIA

Purpose: The presence and degree of regression were assessed from 18 t o 30 months after photorefractive keratectomy (PRK). Methods: A total of 449 eyes (449 patients) were treated with an Aesculap Meditec 193-n m Arf Excimer laser. These 449 eyes were followed during the first 24 months after PRK, and 252 of these eyes were followed for 24 to 30 mon ths, Results: Thirty (6.7%) of the 449 eyes followed for up to 24 mont hs showed good refractive results during the first year and a half but regressed thereafter and required retreatment. Late regression was co nfined to subjects with pretreatment myopia above -4.0 diopters (D) an d was the same in low-and high-myopic eyes between 18 and 24 months po st-PRK. However, between 24 and 30 months, regression was higher in lo w-myopic eyes, where it reached -0.55 D, than in high-myopic eyes, whe re it was -0.21 D. This lower-frequency of regression in high-myopic e yes is attributed to the relatively high rate of retreatment in this g roup during the first 18 months after PRK. Conclusions: Although the f indings indicate a fairly low rate of regression after 24 months, ther e still are insufficient data on which to predict when regression post -PRK stabilizes.