Visual outcomes of photorefractive keratectomy in the treatment of moderate to high astigmatism

Purpose: To evaluate the photorefractive keratectomy (PRK) results in patients with moderate to high astigmatism. Methods: : 112 eyes of 71 patients with a cylindrical component of greater than 3 diopters (D) who have undergone PRK were reviewed retrospectively. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and subjective refraction before and after surgery (1, 3, 6, 12 months) were extracted. Results: : The mean age of patients was 28±6 (33 females and 79 men). The preoperative mean spherical equivalent (SE) was -3.39 ± 1.82 D (range 2.50 to −9.00 D), and the mean cylinder was -3.76 ± 0.78 D (range −3.00 to −6.00 D). The mean postoperative cylinder values were -0.73 ± 0.49 D, -0.72 ± 0.46 D, -0.58 ± 0.48 D, and -0.4 ± 0.63 D at 1- month, 3-month, 6-month, and 12-month visits, respectively. The 12-month efficacy and safety indices were 0.92 ± 0.14 and 0.99 ± 0.10, respectively. The postoperative residual astigmatism was 0.5 D or less in 50% of the eyes. A higher amount of residual astigmatism was observed in the high astigmatism group (Cylinder ≥ 4.00D). Furthermore, postoperative residual astigmatism was correlated with lower preoperative CDVA and mitomycin C time, as well as, higher preoperative cylinder (P <0.001). The target induced astigmatism (TIA), surgically induced astigmatism (SIA), and difference vector (DV) were significantly higher in the high astigmatism group at the 12-month follow-up (p <0.001). The angle of error was ±5 degrees in 71% and ±15 degrees in 99% of the eyes. Conclusions: : PRK is an effective, and predictable method for the correction of moderate to high astigmatism; however, higher residual astigmatism remains in patients with high astigmatism despite the higher levels of correction.