Long-term effect of phacoemulsification on trabeculectomy function.

Abstract

To investigate the long-term effect of phacoemulsification on intraocular pressure (IOP) in trabeculectomized eyes and to identify the factors affecting the IOP changes. In consecutive patients with previous trabeculectomy (TE) who underwent uncomplicated clear cornea phacoemulsification we evaluated intraocular pressure, need of antiglaucomatous medical therapy or glaucoma surgery, and length of glaucoma control without therapy. Glaucoma therapy was prescribed in the presence of IOP >18 mm Hg or worsening of the visual field. A group of trabeculectomized eyes that did not receive cataract surgery was retrospectively selected as a control. Multivariate analysis was used to test factors related to final outcome of the treatment. One hundred and eight eyes with previous TE that received phacoemulsification and 108 controls were included in the study. Phacoemulsification was performed 60±21 months after TE. After a mean follow-up of 66±28 months, mean IOP was significantly increased in the cataract surgery group (by 1.7±4.3 mm Hg) and in the control group (by 2.3±4.3 mm Hg)(both P<0.001); in two groups, respectively, 31 eyes (28.7%) and 17 eyes (15.7%) had received glaucoma therapy (chi-square P=0.030). Factors related to success (no need of therapy) were use of mitomycin-C (MMC) in previous TE (P<0.001), longer time from TE to cataract surgery (P=0.007), higher preoperative bleb score (P=0.021), and lower baseline IOP (P=0.042). Cataract surgery reduces the function of filtering bleb in some eyes. Factors related to low rate of failure are the previous use of MMC during TE, longer time from TE to cataract surgery, and good preoperative aspect of the bleb.