Efficacy of mitomycin C 0.02% for prevention of haze after transepithelial photorefractive keratectomy for mild and moderate myopia

Abstract

Objective: To investigate the efficacy of mitomycin C (MMC) 0.02% for prevention of haze after transepithelial photorefractive keratectomy (Trans-PRK) for mild and moderate myopia. Methods: Retrospective cohort study. We reviewed medical records of 295 patients (588 eyes) who underwent Trans-PRK with or without use of MMC. There were 45 patients (90 eyes) in the mild myopia group (aged between 18 and 41 years; 37 males and 8 females; myopia diopter <3.00 D) and 250 patients (498 eyes) in the moderate myopia group (aged between 18 and 46 years; 168 males and 82 females; myopia diopter: 3.00 to 6.00 D). The two groups were divided into subgroups with MMC 0.02% and without MMC, respectively. The time of intraoperative application of MMC, if there was, was 15 s and 30 s in the mild myopia group and the moderate myopia group, respectively. The mean follow-up time was 6 months. Postoperative best corrected visual acuity (BCVA), spherical equivalent (SE) and haze were analyzed and compared using an independent Student t-test or Mann-Whitney U test between subgroups. Haze variables were compared using chi-square statistics. Results: Haze was quantified with Fantes from grade 0.5 to 4. In the mild myopia group, all haze grades were 0.5 within 3 months. The incidence of haze was 6.25% (2/32) in eyes treated with MMC and 8.62% (5/58) in eyes treated without MMC; there was no statistical significance (χ²=0.00, P>0.999). In the moderate myopia group, the incidence of haze was 9.19% (24/261) in eyes treated with MMC within 3 months; the grade was 0.5 in 91.67% (22/24) of eyes with haze and 1 in 8.33% (2/24). The incidence of haze was 29.53% (70/237) in eyes treated without MMC; the grade was 0.5 in 60.00% (42/70) of eyes with haze, 1 in 18.57% (13/70), and 2 in 5.71% (4/70) within 3 months, and 0.5 in 15.71% (11/70) after 3 months (χ²=12.36, P=0.002). In the mild myopia group, BCVA was 5.0(5.0, 5.1) versus 5.0(5.0, 5.1) in the subgroups with MMC and without MMC (Z=-0.34, P=0.733). In the moderate myopia group, BCVA was 5.0(5.0, 5.1) versus 5.0(5.0, 5.1) in the subgroups with and without MMC (Z=-2.05, P=0.040). In the mild myopia group, SE was (0.33±1.07) D versus (0.32±0.57) D in the subgroups with and without MMC (t=0.25, P=0.805). In the moderate myopia group, SE was (0.66±0.85) D versus (0.53±0.67) D in the subgroups with and without MMC (t=2.97, P=0.003). Conclusions: MMC 0.02% was effective in preventing haze after Trans-PRK in the treatment of moderate myopia. However, it was not effective in mild myopia.