We read carefully the letter of Dr Gebhardt, and we thank him for his concern regarding the potential carcinogenic properties of mitomycin. Mitomycin has been reported as carcinogenic and mutagenic in rodents after repeated intravenous or subcutaneous administrations of 0.5 mg/kg per day.1 A comparable amount in humans might be 35 to 40 mg/d of mitomycin (intravenously or subcutaneously). We delivered a single subconjuctival injection of 1 mg of mitomycin, a dosage which, as detailed in the "Comment" section,2 is far lower than that routinely used in the treatment of recurrent pterygium in humans.3 Again, the 0.4% mitomycin-soaked sponge that is currently applied under the conjunctiva during a filtering procedure4 contains at least 2 mg of mitomycin (twice as much as the amount adopted in our study). Our experiments were, therefore, performed in a much safer condition as far as drug toxicity is concerned
Gandolfi SA, Vecchi M, Braccio L. Decrease of Intraocular Pressure After Subconjunctival Injection of Mitomycin in Human Glaucoma-Reply. Arch Ophthalmol. 1996;114(10):1298. doi:10.1001/archopht.1996.01100140498038
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