Abstract
Purpose: :
To evaluate the results of the prophylactic use of 0.01 mg/ml mitomycin–C (MMC) to inhibit haze formation after excimer laser photorefractive keratectomy (PRK).
Methods: :
This is a prospective, descriptive and longitudinal study. The inclusion criteria were a spherical equivalent correction over –4.00 diopters (D) and inadequate corneal thickness to allow a LASIK procedure. Briefly, the standard PRK technique was with alcohol un–epithelialization, and laser ablation with Chiron Technolas 217. After PRK eyes were treated with a soaked microsponge with MMC placed over the ablated area during 1 minute and rinsing with BSS 20 cc. Soft contact lens until complete re–epithelialization was placed. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), slit lamp examination, refractive error, evidence of corneal haze (classified into 4 grades), specular microscopy and confocal microscopy were done.
Results: :
Thirty eyes of 15 patients were included. Mean age was 27.8 years old. Preoperative spherical equivalent in average was –4.54 D. The average preoperative UCVA was 20/400 and 20/25 in 86.65% of cases postoperatively. No patient had loss in BCVA. No moderate or severe toxic, or side effects were observed postoperatively. Only 10% had grade 1 haze, none had higher than grade 1 during the 3 months of follow up. Specular Microscopy showed mean endothelial cell density of 2,632 cells/mm2 preoperatively and 2,655 cells/mm2 postoperatively. By confocal microscopy superficial epithelial cells acquired normal density and morphology at 1 month postoperatively, basal cells had a normal density after 3 months but remain irregular, the amount of activated keratocytes increased slowly during the first 3 months, the organization of extra cellular matrix and collagen lamellae was normal until the 3° month.
Conclusions: :
The prophylactic use of 0.01% mitomycin–C solution applied intra–operatively in a single dose after PRK decrease the incidence of haze.
Keywords: microscopy: confocal/tunneling • refractive surgery: PRK • drug toxicity/drug effects