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Baerveldt 250-mm2 glaucoma device appears more effective at lowering IOP than is Ahmed implant, retrospective study reveals

Wednesday, July 30 2008 | Comments

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What's This? Advanced Medical Optics Inc.'s Baerveldt 250-mm2 Glaucoma Implant may be more effective at lowering intraocular pressure (IOP) in the treatment of refractory glaucoma than is New World Medical Inc.'s Ahmed S2 Glaucoma Valve, a comparison study reveals.

For the retrospective, interventional case series, researchers compared 59 eyes of 59 patients who received the Ahmed product and 133 eyes of 133 patients who received the Baerveldt product at Indiana University from March 1996 to December 2003. Both drainage devices were placed by one of two attending physicians. Patients followed a postoperative drug regimen, and glaucoma drugs could be restarted to control IOP if judged clinically necessary.

Success was defined as IOP greater than 5 mm Hg and less than 22 mm Hg and at least a 20 percent reduction in IOP from preoperative IOP (with or without glaucoma medications) and without loss of light perception. Secondary outcome measures were IOP, visual acuity (VA), number of glaucoma medications and surgical complications. Follow-up, which lasted until last documented visit or date of failure, spanned a mean 20 months for Ahmed eyes and 22.9 months for Baerveldt eyes.

Cumulative successes in the Ahmed group were 0.73 at one year and 0.62 at two years, whereas cumulative successes in the Baerveldt group were 0.92 at one year and 0.85 at two years. Thus, the rates of success were significantly higher in the Baeveldt group than in the Ahmed arm.

At last follow-up visit, eyes in the Ahmed group had a significantly higher mean IOP (19.8 mm Hg vs. 15.8 mm Hg) and used significantly more glaucoma medications (average, 1.4 medications vs. 0.9 medications) than did eyes in the Baerveldt group. Both groups showed significantly worse final VA relative to preoperative VA; complication rates between the two arms were also comparable.

Two methods for avoiding hypotony after Baerveldt implantation had similar outcomes. Additionally, male gender, African descent, neovascular glaucoma and Ahmed implantation were found to be significant predictors of implant failure in multivariate analyses.

"Other studies have found a tendency for lower success rates in neovascular eyes undergoing glaucoma implants; however, as far as we can tell our study is the only one to demonstrate neovascular glaucoma as a significant risk factor," the authors said. "Other studies will need to be done to confirm these results and to elucidate fully the mechanism of the observations."

Results of the study were reported in the July issue of the journal Ophthalmology.

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