The Effect of Reducing the Exposure Time of Mitomycin C in Glaucoma Filtering Surgery

Background: The use of adjunctive intraoperative mitomycin C has considerably improved the success rate of glaucoma filtering surgery. However, the ideal concentration and exposure time of mitomycin C is unknown. The purpose of this study is to determine whether a satisfactory surgical outcome can be achieved with a lower incidence of adverse side effects by using a shorter exposure time of mitomycin C than has been recommended previously. Methods: Twenty-five eyes of 25 consecutive patients who were considered to be at high risk for surgical failure because of their age (<55 years), previous failure of trabeculectomy, previous cataract surgery, or traumatic glaucoma received a single intraoperative application of mitomycin C (0.2 mg/ml for 2 minutes). They were casematched with a group of 48 consecutive patients who received a single intraoperative application of mitomycin C (0.2 mg/ml for 5 minutes) by using age, race, type of refractory glaucoma, and preoperative intraocular pressure (IOP) as variables. Results: Eighteen months after surgery, 22 (88%) patients in the 2-minute group and 21 (84%) patients in the 5-minute group had an IOP less than 21 mmHg with or without treatment. No significant differences were found in the complication rate: in 2 (8%) of 25 eyes of the 2-minute group, chronic hypotony developed compared with 3 (12%) of 25 eyes in the 5-minute group. Hypotony-related maculopathy developed in one eye in the 5-minute group. A cystic bleb was found in 15 (60%)eyes in the 2-minute group compared with 19 (76%) eyes in the 5-minute group, although this difference was not statistically significant. Two (8%)eyes in the 2-minute group and one eye (4%) in the 5-minute group had a bleb-related infection. In one (4%) patient in each group, late severe endophthalmitis developed. Conclusion: These results suggest that a 2-minute intraoperative application of 0.2 mg/ml mitomycin C is as effective as a 5-minute exposure, but the complication rate remains unaltered. © 1995, American Academy of Ophthalmology, Inc. All rights reserved.