Long-term Outcomes of Baerveldt Glaucoma Implant Shunts as a Primary Versus Secondary Procedure

To determine the 5-year success rate for Baerveldt glaucoma implant (BGI) in patients who received the implant as a primary (primary BGI, used as the initial surgical procedure) or secondary (secondary BGI, used after trabeculectomy) by a single surgeon between year 1994 and 2010.

A total of 117 eyes from patients who underwent BGI placement as a primary or secondary procedure were included in this study. Demographics, previous history, type of glaucoma, intraocular pressure (IOP), visual acuity (VA), glaucoma medication use, and early and late postoperative complications were collected. Postoperative data were collected at day 1, 30, 60, and every year until the last visit (minimum of 2 y). IOP was the main outcome measure. Secondary outcome measures included VA, glaucoma medication use, and early and late postoperative complications. Overall success rates were calculated for primary and secondary BGI using Kaplan-Meier survival analysis. Differences between survival curves were determined using log-rank test. Risk factors for success were defined by Cox proportional-hazards regression model.

At the 5-year follow-up, the overall success rates (determined as IOP between 6 and 21 mm Hg) in the primary and secondary BGI were 58% (49/79) and 53% (20/38), respectively (P=0.56). The overall success rate dropped by an average 10% and 13% per year for the primary and secondary BGI groups, respectively (P=0.05). The complete success rates at the 5-year follow-up for primary and secondary BGI were 24% (19/79) and 13% (5/38), respectively, whereas the qualified success rates were 34% (27/79) and 39% (15/38), respectively. There was a significant decrease in IOP [from 31.23 (±9.51) to 12.86 (±4.84) mm Hg (P<0.001) for the primary BGI group, and from 26.35 (±7.22) to 13.92 (±5.90) mm Hg (P<0.001) for the secondary BGI group]. There was also a significant drop in medication use but a significant worsening in VA in both groups (P<0.05) likely from cataract. The difference in the incidence of postoperative complications was not statistically significant between the groups.

Although, the success rates were similar for the primary and secondary BGI at the 5-year follow-up, the drop in the success rate per year was significantly higher in the secondary BGI group. In contrast, both procedures had similar incidence of postoperative complications.