Comparison of Single-Step Transepithelial Photorefractive Keratectomy With or Without Mitomycin C in Mild to Moderate Myopia

Purpose: To compare efficacy and safety of single-step transepithelial photorefractive keratectomy (PRK) with or without mitomycin C (MMC) in patients with mild to moderate myopia.

Methods: Patients with mild to moderate myopia (≤ -5.50 diopters [D]) underwent single-step transepithelial PRK using the Amaris laser (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany). Total ablation depth (epithelium and stroma) was 160 μm or less. The right eye of each patient was treated with 0.02% MMC for 10 seconds, whereas the left eye did not receive any MMC. Corneal haze, endothelial cell indices, refraction, visual acuity, contrast sensitivity, and higher order aberrations were assessed preoperatively and postoperatively.

Results: In this comparative case series, 71 patients (16 men and 55 women; 142 eyes) were enrolled. Mean patient age was 27.97 ± 5.74 years. Mean preoperative spherical equivalent of patients' right and left eyes were -3.20 ± 1.20 and -3.30 ± 1.20 diopters, respectively (P = .70); other preoperative visual parameters were also comparable. Incidence of 2+ grade of haze was detected in 1 (2.5%) right and 2 (5.0%) left eyes (P > .99) 3 to 6 months postoperatively. Incidence of 1+ degree of haze was also comparable. No eye developed 3+ degrees or more of haze. One year postoperatively, both eyes achieved comparable refraction, visual acuity, contrast sensitivity, and higher order aberrations, and no greater than trace haze was detected. MMC-treated eyes suffered a greater loss of endothelial cell density (P < .001) and showed higher variance in cell size (P = .001).

Conclusions: Single-step transepithelial PRK with or without MMC showed similar efficacy and incidence of haze in eyes with mild to moderate myopia with total ablation depths of 160 μm or less. However, MMC-treated eyes showed a worse profile of endothelial cell indices. Applications of MMC in this subgroup of patients may be reconsidered. [J Refract Surg. 2018;34(6):400-407.].