The Choice of Drainage Device in Complicated Glaucomas: Comparing Ahmed and Baerveldt Implants

Glaucoma is a chronic and progressive optic neuropathy which leads to deterioration of visual function. It is estimated to be the second leading cause of severe vision loss and blindness worldwide. Failure of anti-glaucoma medication to sufficiently reduce intraocular pressure (IOP) and poor compliance with medication are indications for glaucoma surgery, for example using glaucoma drainage devices. Our aim was to compare the surgical outcomes following the implantation of Ahmed FP7 and Baerveldt 350 drainage devices.

Five hundred and fifty-two patients with primary or secondary glaucoma were enrolled in the study. All patients had a history of failed trabeculectomy or other intraocular surgery, and IOP ≥18 mm Hg. The implantation of Ahmed (266 patients) or Baerveldt (286 patients) devices was randomly performed in the patients, who were subsequently examined for a period of 5 years. Follow-up visits were scheduled 1 day; 1 week; 1, 3 and 6 months; and 1, 1.5, 2, 3, 4 and 5 years postoperatively.

Significant reduction of IOP was achieved in both groups. Ahmed valve (28.3±9.3, 13.4±6.9, 14.2±6 and 12.7±4.5 mmHg at baseline, 1, 3, and 5 years postoperatively, respectively) resulted in significantly greater IOP reduction compared to Baerveldt implant (29.6±10.1, 15.4±5.5, 14.5±5.5 and 14.7±4.4 mmHg at baseline, 1, 3, and 5 years postoperatively, respectively). A significantly lower number of medications was required in the Ahmed group in comparison to the Baerveldt one (Ahmed group: 1.5±1.4, 1.4±1.5 and 1.8±1.5; Baerveldt group: 1.9±1.3, 1.9±1.3 and 2.2±1.4, respectively). The incidence of treatment failure and the rate of glaucoma reoperation were significantly higher in the Baerveldt group (40%) compared to the Ahmed group (17%).

Ahmed drainage implantation seemed to outclass that using the Baerveldt device in our study, in terms of efficacy and success rate.