Objective: To determine the risk factors for development of postoperative hypotony and the effects of hypotony on the outcome of surgery in terms of intraocular pressure (IOP) control and final visual acuity in patients who underwent standard trabeculectomy, trabeculectomy with postoperative 5-fluorouracil injections, trabeculectomy with intraoperative mitomycin-C, or trabeculectomy with both antimetabolites.
Patients and design: We retrospectively reviewed the outcome in 155 eyes of 155 patients who underwent standard trabeculectomy (n = 15), trabeculectomy with postoperative 5-fluorouracil injections (n = 81), trabeculectomy with intraoperative mitomycin-C (n = 55), or trabeculectomy with both antimetabolites (n = 4).
Results: Hypotony developed in 108 (69.6%) eyes (IOP < 6 mm Hg) at some point postoperatively; this was transient (< 14 days) in 75 eyes, and prolonged (> 14 days) in 33 eyes. The positive preoperative factors for the development of prolonged hypotony were young age, myopia, and preoperative use of carbonic anhydrase inhibitor. The mean age of patients in whom prolonged hypotony developed was 57.3 +/- 18.3 years (compare the mean age without prolonged hypotony, 65.3 +/- 14.5 years, p = 0.02). Sixteen of 33 (48%) patients in whom prolonged hypotony developed were myopic (p = 0.02), and 23 of 33 (70%) patients in whom prolonged hypotony developed used preoperative carbonic anhydrase inhibitor (p = 0.07).
Conclusions: There was no difference in the incidence of hypotony between patients who received 5-fluorouracil and those who received mitomycin-C. Postoperative hypotony was associated with three types of postoperative complications: shallow anterior chamber, choroidal detachment, and hypotony maculopathy (p = 0.02, 0.000, and 0.05, respectively). Hypotony did not have any effect on the success of surgery in terms of IOP control, but did have an effect on the visual outcome. Fourteen of the 33 patients (42.4%) in whom prolonged hypotony developed had worse visual acuity (p = 0.002); of these cases, four were due to hypotony maculopathy.