Marc E Rainbow, DVM, DACVO South Texas Veterinary Ophthalmology

North Houston Veterinary Ophthalmology

•Placement of an Ahmed Valve Dorsolateral quadrant 10mm posterior to the limbus

•Cyclophotocoagulation Diode Laser, contact probe Slow Burn Method – 1000msec, 5000mW 25 sites, 4 mm posterior to the limbus Total Energy = 125J

•Postoperative Maintenance Timolol or Dorzolamide bid Latanoprost sid

•Corneal Ulcers •Shunt Obstruction

TPA •Shunt Migration

Posterior Placement •Fibrous Capsule Formation

Mitomycin C Average Development – 6 months to 1 year

•Surgical resection of fibrous capsule • Average Time from Placement of Ahmed Valve– 425days

•Repeat cyclophotocoagulation •Average Control of IOP – 197 days •Complications

Corneal Ulcer Shunt Migration Retrobulbar Cellulitis Fibrous Capsule Formation – seems to form more rapidly

•Developed by New World Medical & Dr Sponsel •3mm incision at posterior aspect of the capsule •Insert phalange into capsule •Secure BDD to capsule with 8-0 Nylon •Create subconjunctival tunnel to retrobulbar space •Insert BDD drain into subconjunctival tunnel

Patient Signalment Etiology Time from SX to BDD

Time of IOP control

Molly Basset, SF, 4 Primary 105 days* 162 + days Dorzolamide bid Latanoprost bid

Charlie Blue Golden, NM, 10 Uveitis 241 days 148 days Euthanized (unrelated)

Kodee Aust Shep, NM, 11 Phaco 402 days 263 + days Timolol bid Latanoprost sid

Jax St Poodle, NM, 5 Uveitis 845 days 23 days Shunt Migration

Molly Schnauzer, SF, 12 Phaco 336 days* 171 + days No Hypotensive

Average 386 days 153 days

* No cyclophotocoagulation

•Limited access to posterior capsule Enter at medial edge of capsule

•Straight BDD Bending of BDD required due to medial incision

•Tight adherence of capsule to valve Lack of space to place phalange Place phalange between valve and sclera

•Incorporate angle into BDD 60 to 90 degrees

•Smaller diameter phalange •Combination Ahmed Valve and BDD

Use at initial placement of Ahmed Valve Possible prevention of fibrous capsule

formation