A new, minimally invasive procedure for dogs with encapsulated Ahmed drainage implants and elevated intraocular pressures: A case series.

Objective: To describe a novel, minimally invasive method for re-establishing aqueous humor outflow in dogs with refractory glaucoma after fibrous encapsulation of their Ahmed drainage implants.

Procedure: Three dogs (4 eyes) underwent trans-capsular implantation of an Alcon EX-PRESS glaucoma filtration device under sedation (2 dogs) or general anesthesia (1 dog). After rotating the eye downwards, a 2 mm incision was made in the conjunctiva/Tenon's capsule overlying the encapsulated Ahmed plate, and later closed with absorbable suture. All eyes received subconjunctival mitomycin-C 0.02 mg.

Results: Mean post-operative follow-up was 341 days (range: 77-530). All eyes were hypertensive pre-operatively (mean IOP: 31.25 ± 7.14 mmHg) despite receiving topical latanoprost (4/4), timolol (4/4), carbonic anhydrase inhibitors (4/4), and demecarium bromide (2/4). Two eyes (dogs 1 and 2) were visual pre-operatively, while 2 eyes (dog 3) displayed equivocal or no vision. Post-operatively, all eyes received timolol and a carbonic anhydrase inhibitor. Other anti-hypertensive medications were discontinued. Immediately following surgery, all eyes were mildly hypotensive (mean IOP: 5.75 ± 1.71 mm Hg). Two of 4 eyes were normotensive and visual until days 90 (dog 2) and 530 (dog 1) (IOP range: 10-16 mm Hg). One eye (dog 3) was normotensive for approximately 150 days, and then hypertension returned. One eye (dog 3) from the start displayed severe uveitis, hypertensive episodes, and was phthisical by the end of follow-up.

Conclusions: Trans-capsular EX-PRESS implantation is a minimally invasive procedure for treatment of refractory glaucoma in dogs with encapsulated Ahmed drainage implants, and further investigation is warranted.