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Clinical outcomes of transepithelial photorefractive keratectomy with epithelial ablation targeting actual epithelial thickness vs default laser platform values

In transepithelial PRK, refractive outcome depends little on preexisting corneal epithelial thickness. There is a concern about the contraction of OZ, especially in lower intended ablations. Purpose: To investigate the clinical outcomes of transepithelial photorefractive keratectomy (tPRK) with actual epithelial thickness vs default software values. Setting: Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran. Design: Prospective controlled study. Methods: Patients with refractive spherical error of −1.50 to −7.00 diopters (D) and refractive astigmatism up to 4.00 D were consecutively enrolled and divided into 2 groups: group 1 undergone tPRK with actual central and peripheral epithelial thickness input in right eyes, group 2 undergone tPRK with actual central and 10 mm higher peripheral epithelial thickness in right eyes. Left eyes in both groups underwent tPRK with default protocol. Outcome measures were induced refractive error, achieved optical zone (OZ), and wasted stromal tissue. Results: 83 patients were included in this study. Mean ± SD of induced spherical equivalent was +0.15 ± 0.39 D and +0.01 ± 0.35 D in right and left eyes of group 1 (P = .01) and +0.04 ± 0.22 D and +0.03 ± 0.23 D in right and left eyes of group 2 (P = .75), respectively. There was no statistically significant difference between wasted tissue between right and left eyes in group 1 and group 2 (P = .77 and P = .49, respectively). OZ contraction was significantly higher in right compared with left eyes in group 1 (P = .05), but not in group 2 (P = .95). Conclusions: In tPRK, refractive outcomes, wasted tissue, and OZ contraction depend little on preexisting corneal epithelial thickness in corneas with normal range epithelial thickness. However, OZ contraction may be a concern in lower amount of ablations.