Long-term evaluation of the use of Ahmed gonioimplants in dogs with primary glaucoma: nine cases (2000-2008)

Objective-To evaluate the outcome and describe the complications associated with use of an Ahmed gonioimplant in the treatment of glaucoma in dogs. Design-Retrospective case series. Animals-9 client-owned sighted dogs (median age, 9 years) with primary glaucoma. Procedures-Medical records of dogs with primary glaucoma that underwent unilateral gonioimplant placement (in 2000 through 2008), during which a temporalis muscle fascia graft (n = 8) or porcine intestinal submucosa (1) was used to cover the implant tube as it exited the globe, were reviewed. All dogs were treated with mitomycin C in the conjunctival pocket intraoperatively and with tissue plasminogen activator immediately after surgery; 1% prednisolone acetate was applied to the implanted eye daily until failure of the implant. Medical intervention or additional surgery was performed when intraocular pressures (IOPs) were > 20 mm Hg or progressively increasing values were detected. Results-After gonioimplant placement, IOP was controlled for a variable period in all dogs. Subsequently, IOP exceeded 20 mm Hg in 7 dogs (median postoperative interval, 326 days). Median interval to vision loss despite interventional surgery was 518 days (range, 152 to 1,220 days). Surgical intervention was necessary in 4 dogs to maintain satisfactory IOP. Implant extrusion attributable to conjunctival dehiscence or necrosis occurred in 4 dogs. At 365 days after surgery, 8 dogs retained vision, and 5 dogs retained vision throughout follow-up. Conclusions and Clinical Relevance-In dogs with medically refractory primary glaucoma, placement of a gonioimplant appears to be effective in maintaining vision. (J Am Vet Med Assoc 2011;238:610-617)