Longitudinal evaluation of posterior corneal power by anterior segment optical coherence tomography 18 months following photorefractive keratectomy

Purpose:To investigate the change in anterior, posterior, and net corneal power more than 18 months after photorefractive keratectomy (PRK) by RTVue anterior segment optical coherence tomography (OCT).Setting:Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.Design:Prospective observational study.Methods:PRK was performed using Technolas TENEO 317 laser platform. Anterior, posterior, and net corneal power was measured by the RTVue-XR anterior segment OCT system with the Pachymetry + Cpwr scan pattern at baseline and months 1, 3, 6, 12, 18, and more than 18 (up to 27) after PRK.Results:Three hundred twenty-six eyes of 163 patients (61 men [37.4%], 102 women [62.6%]; mean age 29.71 years; range 18.5 to 46.5 years) were enrolled in this study. Mean preoperative spherical equivalent was -3.15 ± 1.50 diopter (D) (range -8.37 to -0.62 D). The mean change in net corneal power was 3.052 D, 3.281 D, 3.324 D, 3.114 D, 3.446 D, and 3.972 D at months 1, 3, 6, 12, 18, and more than 18 postoperatively compared with baseline, respectively (P <.001 for all comparisons). The mean change in posterior corneal power at postoperative visits compared with baseline was not statistically significant (P >.1) except for 1 month postoperatively, which increased by 0.13 D (P <.001). Changes in posterior corneal power were not correlated with any of the preoperative clinical and Scheimpflug variables.Conclusions:Posterior corneal power did not change for more than 18 months after PRK, except for an early small increase at 1 month postoperatively.