Abstract
OBJECTIVES: To evaluate the 8-to-10-year safety, efficacy, and predictability of photorefractive keratectomy (PRK) and to assess the risk factors for myopic regression and the role of near-work activity in myopia progression. METHODS: This retrospective study included patients who underwent mechanical PRK and were followed up for 8-10 years. Pre-operative clinical data, including visual acuity, refraction, tomography, optical zone, and ablation depth, were analyzed. Safety, efficacy, and predictability indices were evaluated, and astigmatism correction was assessed using Alpins' vector analysis. Myopic regression was defined as a spherical equivalent <-0.25 D. Risk factors for myopic regression were evaluated using regression analysis, and near-work activity was investigated as a potential factor for myopia progression. RESULTS: Eighty-two patients (mean age 30±5.8 years) completed the follow-up. Pre-operative and post-operative refractive errors were -3.61±1.80 D and -0.12±0.25 D, respectively (p<0.001). Seventy-four percent of patients had post-operative refractive errors within ±0.25 D. The safety, efficacy, and predictability indices were 1, 0.95, and 0.97, respectively. The astigmatism correction index was 1.02±0.78. Myopic regression occurred in 22% of patients. Regression analysis showed that the odds of myopic regression increased by 1.4 times (p=0.04) for each 1 D increase in myopia and by 1.05 times (p=0.04) for each micrometer increase in ablation depth. Conversely, the odds decreased by 0.14 times (p=0.03) with each millimeter increase in corneal diameter. The odds ratio for the time spent on near-work activity was insignificant. CONCLUSION: PRK proved to be a safe, effective, and predictable procedure in the long term. Myopia and ablation depth were significant risk factors for myopic regression, while corneal diameter was protective. Near-work activity did not affect myopia progression. Under-corrected eyes for astigmatism exhibited a higher magnitude of pre-operative astigmatism compared to over-corrected eyes.