Comparison of Standard and Low Dose Intraoperative Mitomycin C in Prevention of Corneal Hazeafter Photorefractive Keratectomy

Abstract

Background: Photorefractive keratectomy is a popular mean to correct refractive errors of the eye and haze formation is one of the most important complications of the surgery. Although standard dose of intraoperative Mitomycin C has shown to be effective in reduction of this complication, potential side effects of Mitomycin C promote us to show if the lower concentration of Mitomycin C has t he same effect.

Methods: 170 eyes of 85 patients enrolled in our prospective interventional study. In each patient one eye randomly assigned to be treated by low dose intraoperative MMC (LDMMC) and other eye by standard dose MMC (SDMMC). Then the patients were followed up to 6 months and refraction, Uncorrected Distant Visual Acuity (UCDVA), Best Corrected Distant Visual Acuity (BCDVA) and haze formation submitted in each postoperative exam. The results from two arms of the study compared by means of statistical methods to reveal if there was a significant difference between two groups.

Results: The mean preoperative refraction in LDMMC eyes was –3.08 (SD 1.65) sphere and 0.92 (SD 0.88) cylinder. These values for SDMMC eyes were –3.25 (SD 1.80) sphere and 0.81 (SD 0.84) cylinder. Mean postoperative sphere in LDMMC group was –0.132 (SD 0.503) and –0.138 (SD 0.484) in 3 and 6 months after PRK. These results was –0.041 (SD 0.501) and –0.076 (SD 0.489) for SDMMC group. Mean postoperative cylinder 3 and 6 month after PRK was 0.435 (SD 0.218) and 0.423 (SD 0.255) In LDMMC group and 0.435 (SD 0.247) and 0.426 (SD 0.261) in SDMMC group. In third month 14 eyes in LDMMC group presented with grade 1 score of clinical haze. From these eyes only 2 still had this haze after 6 month. 7 eyes in SDMMC group had grade 1 clinical haze at third month‑ but no clinical haze was seen at the end of 6th month.

Conclusion: Findings of this study show no meaningful differences in postoperative rate of haze formation by use of standard and low dose intraoperative Mitomycin C. regarding these results low dose Mitomycin C with its lower side effects seems to be superior to standard dose in photorefractive keratectomy.

Keywords: Photorefractive keratectomy, Mito mycin C, Corneal haze