Photorefractive Keratectomy for Myopia; an 8-Year Follow up Study

To evaluate the 8-year results of excimer laser photorefractive keratectomy (PRK) for myopia in terms of safety, stability and late complications. Of 203 myopic patients who underwent PRK with single-step method using NIDEK EC-5000 excimer laser with 5-6 mm ablation zones at Basir Eye Center, Tehran-Iran from 1996 to 1998, 179 eyes of 98 patients who completed 8 years of follow up were included in this study. Results of follow up examinations at 1, 3, 6 and 12 months and 2 and 8 years after surgery were analyzed. Treated eyes were divided into three groups according to preoperative refractive error: low (≤ -6.00 diopter [D]), medium (-6.10 to -10.00 D) and high (> -10.00 D) myopes. Eight years after PRK, emmetropia (within ±1 D) was achieved in 69.1%, 30% and 46.15% of the low, medium and high myopia groups, respectively. Although a small myopic shift occurred up to 8 years after surgery, myopic regression stabilized in all groups within 24 months and was correlated significantly to preoperative spherical equivalent refraction. Corneal haze occurred in 5% especially in medium and high myopic groups but cleared within two years in 89% of cases. Only one eye lost two lines of best spectacle-corrected visual acuity due to corneal haze. According to this study, postoperative refraction remains stable two years after PRK and most cases of corneal haze clear within two years after surgery. Therefore, PRK seems to be a safe and stable surgical procedure in myopic patients.