Risk Factors for the Development of Thin-walled Blebs after Mitomycin C Trabeculectomy

Uhm, Ki Bang; Kim, Tae Wan; Kim, Joon Hyun; Hong, Chul

Abstract

The use of mitomycin C as an adjunct improves the success rate of filtering surgery. Blebs after trabeculectomy with mitomycin C tend to be relatively transparent, thin-walled and cystic. Such a bleb is associated with low intraocular pressure but tends to leak and may predispose an eye to endophthalmitis. However, the incidence and risk factors associated with this complication are not known. To determine the incidence and possible risk factors for the development of thin-walled blebs, case records of 160 eyes of 112 patients who received mitomycin C during trabeculectomy were reviewed. Thin-walled, cystic blebs developed postoperatively in 38 (23.8%) of 160 eyes that underwent trabeculectomy with mitomycin C between 1992 and 1995. As the postoperative follow-up time became longer, a greater development of thinwalled cystic blebs was noted. Characteristics of patients after trabeculectomy with mitomycin C in whom thin-walled blebs developed were compared with those of patients in whom thin-walled blebs did not develop. Factors associated with increased risk were: thin conjunctiva and Tenon's capsule (odds ratio 12.7, 95% confidence interval 2.2 to 73.4, P=0.002), uncomplicated glaucoma (primary open-angle glaucoma >or=50 years, primary angle-closure glaucoma) (odds ratio 3.3, 95% confidence interval 1.5 to 7.0, P=0.002), and systemic hypertension (odds ratio 3.8, 95% confidence interval 1.7 to 8.6, P=0.001).