The Use of MMC During PRK and Its Effect on Postoperative Topical Steroid Requirements

1. Purpose To evaluate the use of mitomycin-C (MMC) as an intraoperative adjunct during photorefractive keratectomy (PRK), its effect on postoperative healing and its ability to reduce the postoperative topical steroid course after the surgery. 2. Research Design This is a single-center, prospective, comparative cohort study. 3. Hypothesis There will not be a significant difference in the refractive corrections amongst the treatment groups, 12 months after surgery. 4. Objectives The primary study objective is to compare the effect of intraoperative MMC and a postoperative short topical steroid taper of 3 weeks, intraoperative MMC and a rapid topical steroid taper of 1 week, and a more commonly accepted postoperative regimen of a 2 month long topical steroid taper without any intraoperative MMC. The primary endpoint evaluated will be objective estimates of refractive error (WaveScan WaveFront™ System) at 12 months post-surgery. Secondarily, the extent of haze formation will be evaluated objectively using densitometry maps generated by automated Scheimpflug imaging of the cornea (Pentacam®). Furthermore, the subjective vision from the patients' perspective will be evaluated by questionnaire. 5. Methodology At the Navy Refractive Surgery Center San Diego (NRSC SD), a total of 300 patients will be enrolled and randomly assigned to three cohorts. PRK will be performed in a standard fashion for all treatment groups. In the first two groups, intraoperative MMC 0.01% for a contact time of 15 seconds will be utilized. During the postoperative period, the first cohort will use the short steroid taper and the second cohort will use the rapid steroid taper. The third cohort will not receive any intraoperative MMC and will self-administer postoperative steroids, tapering for two months. All cohorts will be followed at 1 week, 1 month, 3 months, 6 months and 12 months after the procedure. Standard clinical measures of visual performance will be recorded. Since visually significant corneal haze is relatively rare, corneal densitometry will be used as an objective measure to detect subclinical corneal haze in addition to our usual subjective haze evaluation done by the clinical optometrists. The patients will complete a voluntary questionnaire that evaluates their subjective impression of the refractive surgery, their recovery and their outcomes. Specifically, the patient will report the use of refractive correction, usefulness of the surgery at work, dry eye complaints, and subjective appraisal of their vision.