Comparison of Outcomes Following Glaucoma Drainage Tube Surgery Between Primary and Secondary Glaucomas, and Between Phakic and Pseudophakic eyes

Purpose: To report outcomes of glaucoma drainage device (GDD) surgery based on primary or secondary glaucoma diagnosis and lens status. Design: Single-center, retrospective, consecutive cohort study. Methods: University of Florida patients aged 18 to 93 years who underwent nonvalved GDD surgery between 1996 and 2015 with a minimum of 1-year follow-up were examined. Of the 186 eyes of 186 patients enrolled, 108 had a primary glaucoma and 78 a secondary glaucoma diagnosis. Excluding 13 aphakic patients, 57 eyes were phakic and 116 pseudophakic. Mean intraocular pressure (IOP), mean number of medications, visual acuity (VA), surgical complications, and failure (IOP >18 mm Hg, IOP <6 mm Hg, reoperation for glaucoma, or loss of light perception) were the main outcome measures. Results: No significant difference was noted in mean IOP and mean medication use (12.8 +/- 4.5 and 13.0 +/- 6.6 mm Hg on 2.0 +/- 1.2 and 1.5 +/- 1.1 medication classes, respectively), mean VA (1.08 +/- 0.98 and 0.94 +/- 0.89, respectively), failure, or numbers of complications and reoperations (P > 0.05) between eyes with primary and secondary glaucomas at up to 5 years postoperatively. Comparison of phakic and pseudophakic eyes showed a statistically significant higher success rate for the pseudophakic patient group at the >18 mm Hg upper limit and <6 mm Hg lower limit (P = 0.01), and significantly fewer eyes required reoperation to lower IOP (6.9% vs 23%). Conclusions: GDD surgery appears equally effective for secondary glaucomas as for primary glaucomas, and has a better outcome for pseudophakic eyes than phakic eyes.