The Ahmed shunt versus the Baerveldt shunt for refractory glaucoma: a single-surgeon comparison of outcome.

PURPOSE

To compare the surgical outcome of Baerveldt and Ahmed shunt implants in the treatment of refractory glaucoma.

DESIGN

Retrospective, nonrandomized, comparative trial.

METHODS AND PARTICIPANTS

Medical records of 118 consecutive patients who underwent glaucoma shunt implantation (70 Baerveldt, 48 Ahmed) by a single surgeon were reviewed.

MAIN OUTCOME MEASURES

The primary outcome measure was surgical success (6 mmHg <or= intraocular pressure [IOP] <or= 21 mmHg without additional glaucoma surgery or devastating complication) at 12 months after surgery. Secondary outcome measures included mean IOP and number of medications used at the following postoperative visits: day 1, 1 week, 1 month, 3 months, 6 months, and every 6 months thereafter. Additional outcome measures evaluated include visual acuities, prevalence and timing of postoperative choroidal detachment, and clinical bleb encapsulation.

RESULTS

Survival curve analysis showed success rates of 82.9% of the Ahmed group and 72.9% of the Baerveldt group at 12 months after surgery (P = 0.257). Patients in the Ahmed group exhibited lower IOPs at 1 day (P < 0.001) and 1 week (P < 0.001) after surgery and were taking fewer glaucoma medications at 1 week (P < 0.001) and 1 month (P < 0.001) after surgery. A higher proportion of Ahmed patients experienced clinical bleb encapsulation than did the Baerveldt patients (60.4% vs. 27.1%; P < 0.001). Moreover, the first observation of postoperative bleb encapsulation was sooner after surgery for the Ahmed patients (50.0 +/- 43.8 days) than for the Baerveldt patients (69.8 +/- 22.6 days; P = 0.001).

CONCLUSIONS

The Ahmed shunt implant exhibited better control of IOP in the early postoperative period (1 day and 1 week) with patients requiring fewer glaucoma medications at 1 week and 1 month after surgery. There was both a higher prevalence and earlier onset of bleb encapsulation observed with the Ahmed shunt implant.