Abstract
Purpose: :
To evaluate and compare the effect of the prophylactic use of two different exposure times of mitomycin C (MMC) 0.02% to inhibit haze formation after photorefractive keratectomy (PRK) for high myopia (> -7.0 D).
Methods: :
Forty six eyes of twenty three patients, 8 men and 15 women, with high myopia were included in this prospective study. Mean age at the time of PRK plus MMC was 31.7 years. Before PRK, the mean spherical equivalent was -8.50 D (range, -7.25 to -10.50 D). In each patient, one eye was randomly assigned to PRK and a single intraoperative topical application of mitomycin C 0.02% for 15 seconds (Group 1) and the fellow eye, for 30 seconds (Group 2).The inclusion criteria were high myopia, no central corneal opacity and inadequate corneal thickness to allow a safe Laser in situ keratomileusis procedure. Refraction, uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), and slit-lamp evidence of corneal opacity (haze) were evaluated over 12 months.
Results: :
No adverse effects related to the use of mitomycin C were observed during re-epithelialization or during follow up. Twelve months postoperatively, 2 eyes (8.69 %) from Group 1 showed grade 1 haze, and one eye showed grade 0.5 haze (4.34%). No eye from Group 2 developed haze at any time after surgery. Two eyes from Group 1 (8.69 %) lost one line of the BSCVA as compared to the pre-PRK values. Mean final spherical equivalent achieved was: -0.50 ± 0.22 D in Group 1 and +0.25 ± 0.18 D in Group 2. No eye needed retreatment for refractive correction.
Conclusions: :
The prophylactic use of a single intraoperative topical application of mitomycin C 0.02% for 30 seconds seems to be more effective to inhibit haze formation after PRK for high myopia when compared to mitomycin C 0.02% for 15 seconds.
Clinical Trial: :
www.clinicaltrials.gov NCT00564213
Keywords: refractive surgery: PRK • refractive surgery: optical quality • refractive surgery