A long-term study of photorefractive keratectomy*112-year follow-up

Abstract

Objective To evaluate long-term refractive stability of excimer laser myopic photorefractive keratectomy (PRK). Design A long-term (12 years) prospective follow-up study. Participants Sixty-eight patients (56.6%) of the original cohort of 120 who participated in the first United Kingdom excimer laser clinical trial underwent detailed clinical assessment at 12 years after myopic PRK. Intervention Myopic PRK was performed using the Summit Technology UV 200 excimer laser with a 4-mm ablation zone. Patients were allocated to 1 of 6 treatment groups based on their preoperative refraction. Each group received one of the following spherical corrections: −2, −3, −4, −5, −6, or −7 diopters (D). Patients in each group received an identical treatment, and therefore, emmetropia was not the primary aim. Main outcome measures Refractive stability, refractive predictability, best spectacle-corrected visual acuity (BSCVA), and corneal haze. Results The postoperative refraction remained stable at 12 years, with no significant change in mean spherical equivalent refraction between 1, 6, and 12 years. Seventy-five percent of patients who underwent a −2-D correction and 65% of patients who received a −3-D correction were within 1 D of intended correction at 12 years. Fifty-seven percent of the −4-D group and 50% of the −5-D group were within 1 D, and this was further reduced to 25% and 22% in the −6-D and −7-D groups, respectively. Four percent had residual corneal haze, and 12% had persistent nighttime halos at 12 years. Dry eyes were encountered in 3% of patients, and none of the eyes developed corneal ectasia in the long term. Conclusions In myopic PRK, refractive stability achieved at 1 year was maintained up to 12 years with no evidence of hyperopic shift, diurnal fluctuation, or late regression in the long term. Corneal haze decreased with time, with complete recovery of BSCVA. Night halos remained a significant problem in a subset of patients due to the small ablation zone size.