Clinical features of patients who needed more than one-time photorefractive keratectomy (PRK), a retrospective cohort study

To evaluate the clinical features of patients who had undergone photorefractive keratectomy (PRK) more than once. Identifying these pre-operative parameters can help in assessing patients at higher risk of repeat PRK. A historical cohort study was carried out at Farabi Eye Hospital between 2015 to 2022. The data were obtained from electronic records, refined, and divided into two groups based on PRK outcome: cases that underwent a second round of PRK and controls that underwent PRK only once. Only patients with at least 12 months postoperative follow-up were included. The baseline preoperative data, including subjective & objective refraction, spherical equivalent, anterior and posterior keratometry, and corneal pachymetry at the apex & thinnest location, were collected. The PRK surgery was performed using Schwind Amaris 1050 RS by Sirius CSO, and the anterior segment measurements were taken using Pentacam® HR. Forty eight patients were included, with 17 in the case group who underwent a second round of PRK and 31 in the control group who had a single PRK. The mean ages of the control and case patients were 32.1±7.8 and 31.00±8.62 years, respectively. A statistically significant difference was observed between the control and case groups in the mean subjective sphere (control -3.17±2.77 vs. case 0.07±2.50,P<.001), subjective astigmatism (control -0.90±0.71 vs. case -2.06±1.26,P<.001*), subjective spherical equivalent (SE) (control -3.62±2.77 vs. case-0.96±2.73, P<.001), objective refraction sphere (control -2.75±2.94 vs. case 0.57±3.00, P<.001), objective astigmatic refraction (control -0.91±0.75 vs. case -1.97±1.28, P = .003), and SE of objective refraction (control-3.20±2.30 vs. case -0.41±3.05, P<.001). There were significant differences in anterior flat keratometry (K1) (control 43.93±1.17 vs. case 42.75±1.64, P<0.05) and anterior corneal astigmatism (control 1.03±0.57 vs. case 1.82±1.25, P<0.05) between patients who needed more than one PRK surgery versus those who successfully managed with PRK once. Patients who needed more than one PRK surgery had significantly lower sphere and SE, greater astigmatism, lower anterior flat-K, decreased corneal thickness, and greater anterior corneal astigmatism than patients who needed only one PRK surgery.