Vanderbilt Eye Institute Grand Rounds Vanderbilt Eye Institute 12/15/06 Ryan Tarantola M.D. PGY-2

Initial Evaluation 10/18/06 CC: Elevated IOP OS HPI: 69 yo Female POAG x 10 yrs Treated with gtt and ALT OU IOP OS has been poorly controlled Red eyes OS>OD for many years Referred by outside ophthalmologist for possible filtering procedure.

POH: POAG S/P ALT OU No history of trauma or steroid exposure Allergies: NKDA FH: No hx of eye disease

SH: Denies tobacco, alcohol, or drug use. ROS: Negative Meds: Lumigan OU QHS Azopt OU BID

VAcc at Distance: OD: 20/25 OS: 20/25 Pupils: 42mm, no RAPD OU TA: OD: 19 OS: 26 Visual Fields: FTFC OU Motility: Full OU

OD

OS

Slit Lamp Exam: External: WNL OU Lids/Lashes: Clear OU Conjunctiva: Engorged episcleral veins OS>OD

Slit Lamp Exam cont.: Cornea: Clear OU AC: D/Q OU Lens: 2+ NSC OU

Slit Lamp Exam cont.: Gonioscopy: Open to SS/CBB 360 degrees OU No PAS/NV Blood in Schlemm's canal OS Pachymetry: OD:599 OS:600

Dilated Fundus Exam: Vitreous: Clear OU Optic Nerves: C/D: OD:0.5 OS:0.6 Small nerves OU Thin inferiorly OS>OD Macula: WNL OU Periphery: WNL OU

Questions?

IOP=F/C + Pe Goldmann Equation F=Rate of Aqueous Formation (normally 2-3 µl/min) C=Facility of Outflow (normally 0.2 to 0.3 µl/min/mmHg) Pe=Episcleral venous pressure (normally 8 to 10 mmHg)

Three Routes of Orbital Venous Drainage 1. Superior Ophthalmic Vein Cavernous Sinus Schlemm’s Canal Internal Jugular Vein Deep and Mid Scleral Venous plexus Superior Vena Cava Anastamose 2. Inferior Ophthalmic Vein Pterygoid Plexus 3. Facial and Angular Vein External Jugular Vein

Orbital Venous Drainage Supraorbital v. Nasofronal v. Sup. Ophthalmic v. Nasal v. Cavernous sinus Inf. Ophthalmic v. Angular v. Infaorbital v. Ant. Facial v. Pterygoid plexus

Differential Diagnosis? 69 yo female with previous diagnosis of POAG Elevated IOP OS>OD Engorged episcleral veins OS>OD Blood in Schlemm’s canal OS Differential Diagnosis?

Differential Diagnosis Venous Obstruction a. Thyroid Ophthalmopathy b. Superior Vena Cava Syndrome c. Retrobulbar Tumor d. Cavernous Sinus or Orbital Vein Thrombosis e. Episcleral or Orbital Vein Vasculitis Arteriovenous Anomalies a. Carotid-Cavernous Fistula b. Carotid-Dural Fistula c. Sturge Weber Glaucoma d. Orbital Varix 3. Idiopathic

Additional History Despite 360o ALT OU and maximal medical therapy IOP has never been significantly lowered Patient reports that she has experienced episodic tinnitus in the left ear

Additional Testing?

Auscultation: No orbital bruit appreciated Cerebral Angiogram: Additional Testing Hertel: Base 96mm OD:16mm OS:17mm Auscultation: No orbital bruit appreciated Cerebral Angiogram: Unremarkable anterior and posterior intracranial circulation. No evidence of carotid cavernous fistula No evidence of flow-limiting stenosis, aneurysm, occlusion, or malformation.

Idiopathic Elevated Episcleral Venous Pressure Presentation: Typically presents in elderly with no FH Most cases are unilateral Familial cases have been reported but typically sporadic Often have previous diagnosis of POAG Often complain of red eye

Idiopathic Elevated Episcleral Venous Pressure Signs/Symptoms: Elevated IOP despite medical therapy Tortuous dilated episcleral veins Open-angle glaucoma with characteristic nerve and fields Blood in Schlemm’s canal on gonioscopy No exophthalmos Ruled out other etiologies of increased EVP

Idiopathic Elevated Episcleral Venous Pressure Diagnostic Testing: Orbital ultrasound/MRI: Evaluate retrobulbar space MRA: Detect carotid-cavernous or dural-cavernous fistula Carotid Angiography: Gold standard to rule out fistula Endocrine workup: Evaluated for Thyroid eye disease Hertel: Detect exophthalmos Auscultation: Detect orbital bruit

Idiopathic Elevated Episcleral Venous Pressure Management: Medical: b-blockers a2 agonists Carbonic Anhydrase inhibitors Surgical: Trabeculectomy Tube Shunt Nonpenetrating deep sclerectomy Increased risk of uveal effusion and expulsive hemorrhage Recommended that prophylactic sclerotomies be routinely performed during surgery

Our Patient Follow up visit 10/26/06: IOP OD:22 OS:30 Follow up 11/15/06: IOP OD:22 OS:34 Elected to proceed with ExPRESS mini glaucoma shunt procedure.

ExPRESS Mini Glaucoma Shunt Biocompatible miniature stainless steel implant Previously placed directly beneath conjunctiva but caused many complications In newer technique shunt is placed beneath a scleral flap Diverts aqueous humor to a subconjunctival filtration bleb

A 6 × 3 mm fornix-based conjunctival flap is created in the upper quadrant.

A 50% depth, 5 × 5 mm limbal-based scleral flap is created. Mitomycin C may be applied beneath the flap at the surgeons discretion

With a 26-gauge needle, a pre-perforation is made into the anterior chamber under the scleral flap, in the center of the blue-gray transition zone between the white sclera and clear cornea.

The glaucoma drain is inserted into the anterior chamber via the perforation site.

The scleral flap is then securely sutured with 10-0 nylon sutures.

The conjunctiva is sutured back in place with 1 or 2 buried 8/0 absorbable sutures.

ExPRESS Mini Glaucoma Shunt Ex-PRESS implant inserted in 24 eyes of 23 patients with severe OAG Sixteen eyes of the 24 (66%) had had previous failed filtering surgery Remaining 8 eyes (33%) were high risk for failures cases IOP was reduced from 27.2 ± 7.1 mm Hg pre-op to: 14.5 ± 5.0 mm Hg at 12 months (n = 21) 14.2 ± 4.2 mm Hg at 24 months (n = 8) Two patients needed anti-glaucoma meds to keep IOP below 21 mm Hg Dahan et. al. Implantation of a Miniature Glaucoma Device Under a Scleral Flap. Journal of Glaucoma. April 2005. 14(2):98-102.

ExPRESS Mini Glaucoma Shunt Dahan et. al. Implantation of a Miniature Glaucoma Device Under a Scleral Flap. Journal of Glaucoma. April 2005. 14(2):98-102.

ExPRESS Mini Glaucoma Shunt Dahan et. al. Implantation of a Miniature Glaucoma Device Under a Scleral Flap. Journal of Glaucoma. April 2005. 14(2):98-102.

Take Home Points Understand the venous drainage of the orbit and how abnormalities can result in elevated EVP and thus elevated IOP. Be suspicious of elevated EVP in patients previously diagnosed with POAG. Know the possible causes of elevated EVP and how to evaluate for each. Be aware that the ExPRESS mini glaucoma shunt is a new procedure that appears to be safe and effective at lowering IOP in Glaucoma patients when placed beneath a scleral flap.

References Allingham et al. Shields’ Textbook of Glaucoma p.347-352 Clayton et al. CT angiography and MR angiography in the Evaluation of Carotid Cavernous Sinus Fistula Prior to Embolization: A Comparison of Techniques. Am J Neuroradiol. 26:2349-2356. October 2005. Dahan et al. Implantation of a Miniature Glaucoma Device under a Scleral Flap. J Glaucoma 2005;14:98-102. Greenfield et al. Glaucoma associated with elevated episcleral venous pressure. J Glaucoma 2000 9:190-194. 5. John et al. Dural and Carotid Cavernous Sinus Fistulas. Ophthalmology 94:1585-1600. 6. Moses et al. Mechanism of Glaucoma secondary to increased venous pressure. Arch Ophthalmol. 1985;103:1701. 7. Talusan et al. Increased Pressure of dilated episcleral veins with open-angle glaucoma without exophthalmos. Ophthalmology 1983;90:257.