Studies provide guidance for MMC use

Results of retrospective studies of eyes undergoing surface ablation treatments at the Cole Eye Institute, Cleveland Clinic, Cleveland, OH, are suggesting an algorithm for using mitomycin-C (MMC) to prevent haze, said Ronald S. Krueger, MD, MSE, at Refractive Surgery Subspecialty Day.

Dr. Krueger presented the findings from two studies designed to evaluate the level of corneal haze and the efficacy, predictability, and safety of using topical low dose, 0.002% MMC and high (standard) dose, 0.02% MMC applied to the stromal bed after surface laser treatment. He is medical director, refractive surgery, Cole Eye Institute.

An initial analysis compared outcomes in 84 eyes treated with 0.002% MMC for varying durations of exposure depending on the amount of correction versus in 91 eyes that underwent surgery without MMC. Using multivariate statistical techniques to adjust for some baseline differences between the two groups, the results showed that at 1, 2, 3, 6, 12, and 24 months, haze scores were significantly lower in eyes treated with MMC compared with the controls. When the subjects were divided into three subgroups based on level of myopia, the difference favoring MMC persisted in all three groups.

A second retrospective analysis compared all eyes treated with the standard dose of MMC from 2002 to 2004 against eyes treated during 2005 and 2006 with a low dose. In follow-up visits through 12 months, there was significantly more haze in the low dose MMC eyes at all time points. Subgroup analyses showed significant differences at the 1, 3, 6, 9, and 12 month visits were present only in eyes treated for an SE ≥6 D and when the ablation depth exceeded 75 µm. In eyes with less myopia or shallower ablations, significant differences in haze scores were present only at 1 and 3 months.

"From the first study, one might conclude that low-dose MMC should be used in all surface ablation patients. However, we found it was not the whole story," Dr. Krueger said. "Further analyses are needed, but preliminarily, we are suggesting using the standard dose of MMC for higher corrections and either low dose or no MMC when treating myopia less than -6 D.-