Effect of Subconjuctival Mitomycin–c Injection on Intraocular Pressure

Abstract

Purpose: : To determine the effect of subconjunctival mitomycin–C (MMC) injection used before bare sclera pterygium excision on intraocular pressure (IOP).

Methods: : We performed a retrospective study of patients injected with MMC subconjunctivally before bare sclera removal of pterygia at the John H. Stroger, Jr. Hospital of Cook County Division of Ophthalmology from 7/2/05 to 10/13/05. An injection of 0.5 cc of 0.05 mg/ml of MMC was given under the belly of the pterygium at least one month prior to bare sclera excision. IOP was measured prior to the MMC injection and again before bare sclera pterygium excision.

Results: : Twenty eyes of 20 patients were included in the study. The mean age was 40.85 years (range 24–70 years). Sixteen of the injections were given for pterygia located nasally and four temporally. Before and after the MMC injection, 11 patients were being treated with topical ketorolac (Acular) and artificial tears, one with Visine, and one with Maxitrol drops. Seven patients were not receiving any topical medications. Nineteen patients had no other ocular conditions. One patient had pigment dispersion syndrome. Mean follow up from the time of MMC injection was 43.1 days (range 28–62 days). Mean baseline pre–injection IOP was 15.25 mmHg (SD 2.22). Mean post–injection IOP was 14 mmHg (SD 2.45). This difference was not statistically significant (p = 0.088156) (95% CI).

Conclusions: : Prior animal studies have shown that MMC may have a toxic effect on the nonpigmented epithelium of the ciliary body when given subconjunctivally or on bare sclera. This may have an inhibitory effect on aqueous humor production. Our study showed that subconjunctival MMC injections given for aid in pterygium excision have no effect on IOP. This may be explained by the low concentration of MMC that was used in these patients. Higher concentrations are normally used in glaucoma filtering surgery. The limitations of our study include small sample size and limited follow–up period. Further study is needed to determine if subconjunctival MMC has an effect on the human ciliary body.

Keywords: intraocular pressure • ciliary body • clinical (human) or epidemiologic studies: outcomes/complications