The Effect of Trabeculectomy on Intraocular Pressure (IOP) of the Contralateral Eye

Abstract

Purpose: : To study the changes in intraocular pressure (IOP) in the non–operated contralateral eye of a group of patients that underwent trabeculectomy.

Methods: : A retrospective chart review of 33 participants in the Collaborative Initial Glaucoma Treatment Study (CIGTS) who underwent primary trabeculectomy for newly discovered open angle glaucoma and received no antiglaucoma medications in either eye or surgery in the fellow eye for 3 months postoperatively. Intraocular pressure readings in the operated and non–operated eyes were evaluated at day 1 and at month 1 and month 3 postoperatively and compared to a mean baseline preoperative value. Intraocular pressure readings were obtained in a masked fashion following standard NIH protocols.

Results: : In the operated eye, IOP decreased from a preoperative value of 27.8 ± 4.6 mmHg to 14.7 ± 7.7 mmHg at the first postoperative day. This tendency was maintained at 1 month (13.2 ± 5.0 mmHg) and at 3 months (13.2 ± 5.1 mmHg). In the non–operated eye, IOP decreased from a baseline mean of 25.2 ± 5.4 mmHg to 21.8 ± 4.6 mmHg on day 1 (P = 0.007, paired t–test) and continued to be lower at 1 month (21.5 ± 4.7 mmHg, P = 0.004) and at 3 months (21.7± 5 mmHg, P = 0.008).

Conclusions: : There was a statistically significant IOP reduction in the unoperated eye of previously untreated patients who underwent primary trabeculectomy for open–angle glaucoma. The mechanism explaining this finding is unknown.

Keywords: intraocular pressure