Date of Award

January 2012

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

James C. Tsai

Second Advisor

Iqbal I. Ahmed

Subject Area(s)

Ophthalmology, Medicine, Surgery

Abstract

Purpose: The Ahmed Versus Baerveldt Study is a prospective, international, multicenter, randomized clinical trial which compares the two most frequently used aqueous drainage devices for the treatment of refractory glaucoma.

Methods: Patients aged 18 or older with uncontrolled glaucoma refractory to medicinal, laser and traditional surgical therapy were randomized to undergo implantation of an Ahmed-FP7 valve implant (New World Medical, Inc., Rancho Cucamonga, CA) or a Baerveldt-350 implant (Abbott Medical Optics, Inc., Santa Ana, CA) to be followed for 5-years.

Outcome Measures: The primary outcome measure is failure, defined as intraocular pressure (IOP) out of target range (5-18 mmHg with >20% reduction from baseline) for two consecutive visits after 3 months, vision-threatening complications, additional glaucoma procedures, or loss of light perception. Secondary outcome measures include IOP, medication use, visual acuity, complications, and interventions.

Results: A total of 238 patients were enrolled in the study; 124 received the Ahmed-FP7 valve implant and 114 received the Baerveldt-350 implant. The two treatment groups did not differ in any baseline demographic or ocular characteristics with the exception of sex. The mean age of the study group was 66±16 years and 55% were women. The mean baseline IOP of the study group was 31.4±10.8 mmHg on a mean of 3.1±1.0 glaucoma medications. The median Snellen visual acuity was 20/100, mean number of previous laser therapies was 0.9±1.1, and mean number of previous surgeries was 1.7±1.2. Five (4%) patients in the Ahmed group and 4 (4%) patients in the Baerveldt group experienced significant intraoperative complications (p=1.0). The cumulative probability of failure at 3-years was 51% in the Ahmed group and 34% in the Baerveldt group (p=0.026). The mean IOP at 3-years was 15.7±4.8 mmHg in the Ahmed group (49% reduction from baseline, p<0.001) and 14.4±5.0 mmHg in the Baerveldt group (55% reduction from baseline, p<0.001; comparison between groups: p=0.08). The mean number of glaucoma medications required was 1.8±1.4 in the Ahmed group (42% reduction from baseline, p<0.001) and 1.1±1.3 in the Baerveldt group (65% reduction from baseline, p<0.001; comparison between groups: p=0.002). There was a moderate but similar decrease in visual acuity in both groups (p<0.001). The two groups had similar complication rates (52% Ahmed vs. 62% Baerveldt, p=0.12), however, the Baerveldt group had a higher rate of hypotony-related devastating complications (Ahmed 0%, Baerveldt 7%, p=0.002). Also, the Baerveldt group required a greater number of interventions (73 Ahmed vs. 103 Baerveldt, p=0.006; 38% Ahmed vs. 50% Baerveldt, p=0.07). Overall, most complications were transient and most interventions were minor slit-lamp procedures.

Conclusions: Both devices were effective in reducing IOP and glaucoma medications. The Baerveldt group had a lower failure rate and required fewer medications than the Ahmed group after 3-years of follow-up, but suffered from a higher rate of hypotony-related devastating complications and required more interventions.

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