The effect of trabeculectomy on the intraocular pressure of the unoperated fellow eye

Purpose: To investigate the intraocular pressure (IOP) changes in the unoperated fellow eye in patients who underwent trabeculectomy. Materials and Methods: IOP changes in the unoperated fellow eyes of 107 patients who underwent trabeculectomy in 1 eye for high-tension glaucoma (48 primary open-angle glaucoma, 43 pseudoexfoliative glaucoma, and 16 narrow-angle glaucoma) were evaluated during the early postoperative period. All IOP measurements were recorded during the postoperative first 3 months and compared with preoperative values. Results: Mean preoperative IOP levels were 37.0 +/- 10.0 mm Hg in the operated eyes and 15.1 +/- 3.1 mm Hg in the fellow eyes. Mean ION in the unoperated eyes on the postoperative first-day, first- and second-week, and first- and third-month visits (17.1 +/- 5.7, 17.5 +/- 5.1, 18.5 +/- 5.4, 18.6 +/- 5.1, and 19.0 +/- 5.9 mm Hg, respectively) were significantly different compared with the preoperative levels for each period of time (P < 0.01). Eight fellow eyes underwent operations for uncontrolled glaucoma before month 3. Among the remaining 99 eyes, higher postoperative IOP values were measured in 33 (33%) eyes at all postoperative visits compared with the preoperative IOP levels. A consistent IOP rise equal to or higher than 5 mm Hg was detected in 12 eyes (12%) and a consistent IOP elevation of 30% or more was found in 14 eyes (14%) during the postoperative first 3 months. Contralateral IOP elevation was not correlated with patient age, type of glaucoma, or preoperative antiglaucomatous medications prescribed to the operated or fellow eyes. Conclusion: After filtration surgery, IOP of the unoperated fellow eye should also be monitored closely in order not to overlook a possible insidious rise, especially in glaucomatous eyes that were previously under good medical control.