Effect of Photorefractive Keratectomy Using Three Methods in Myopic Eyes with Astigmatism <1.00 D

To compare the results of Photorefractive Keratectomy (PRK), surgery was performed using three Conventional, Iris Registration, and Spherical Equivalent methods in correcting astigmatism In the current cohort study, 72 myopic eyes (40 patients) with astigmatism less than 1.00 D were randomly divided into 3 groups (Conventional, Iris Registration, and Spherical Equivalent) and were respectively reviewed. In the first group, the excimer laser changed the corneal curvature regardless of the rotation of the eye. In the second group, a high resolution photo of the iris was provided before surgery and the amount of rotation of the eye in the lying state was measured related to the sitting. Finally, in the last group, half of power of the cylinder was added to the sphere and regardless of the rotation and axis of cylinder, the surgery was performed. Residual astigmatism and outcomes were compared with initial data six months postoperatively. The mean age of patients was 28.19±5.35. Preoperative BCVA was 10/10 in all patients. No statistical difference was noticed between the groups (p>0.05) in the preoperative astigmatism. In Conventional PRK group, the average astigmatism decreased from-0.48±0.30 D preoperatively to -0.19±0.20D postoperatively (p=0.002) and the average astigmatism in Iris Registration PRK group decreased from -0.54±0.19D preoperatively to -0.18±0.21D postoperatively (P<0.001), compared with the increased astigmatism in Spherical Equivalent PRK group from -0.55±0.12D preoperatively to -0.65±0.16D postoperatively (p=0.008). The average myopia decreased from -3.90±1.04 to 0.04±0.35D in Conventional group, decreased from -3.77±1.04 to 0.44±0.35 in Iris Registration group, and decreased from -2.58±1.11 to 0.14±0.28 in Spherical Equivalent group. According to the results, Conventional and Iris Registration PRK decreased the amount of postoperative astigmatism more than Spherical Equivalent PRK. The amount of postoperative myopia decreased in the three groups.