• 6 SECTIONGlaucoma Angle Open

Elevated Episcleral Pressure

Possible Causes

•Carotid cavernous fistula

•Dural sinus fistula

•Graves orbitopathy

•Idiopathic

•Orbital varix

•Sturge–Weber syndrome

•Superior vena cava syndrome

•Retrobulbar tumor

Key Facts

•Uncommon form of glaucoma

•Unilateral (more common) or bilateral

•Diagnosing cause of increased episcleral pressure is key

Mechanism

•High IOP due to increased outflow resistance with higher than average episcleral vein pressure

•(Population average episcleral venous pressure is 8–10 mmHg)

Clinical Findings

•Blood visible in Schlemm’s canal on gonioscopy (Fig. 6.22)

•Dilated and/or tortuous episcleral vessels (Fig. 6.23)

•Glaucomatous optic nerve changes

•Occasionally low-grade anterior chamber flare or cell

Ancillary Testing

•Gonioscopy: blood in Schlemm’s canal is key finding

•See Primary open angle glaucoma (p. 60)

•Thyroid studies

•Orbital imaging (B scan, CT, MRI)

•Angiography or magnetic resonance angiography

Differential Diagnosis

•Primary open angle glaucoma

•Conjunctivitis

•Episcleritis

•Inflammatory glaucoma

Treatment

•Treat underlying cause, if known

•Increased chance of suprachoroidal hemorrhage with incisional surgery

•Responds better to topical therapy targeting aqueous production than topical therapy targeting outflow facility

Prognosis

• Good prognosis if discovered early

Fig. 6.22 Blood in Schlemm’s canal (yellow arrow).

Fig. 6.23 Dilated episcleral vessels.

Pressure Episcleral Elevated

• 6 SECTIONGlaucoma Angle Open

Sturge–Weber Syndrome

(Encephalotrigeminal Angiomatosis)

Key Facts

•Incidence is 1 in 50 000 in the USA

•No race or sex predilection

•Angiomas of the leptomeninges and facial skin (V1 and V2 distribution)

•Port wine stain angioma of facial skin

•Seizures and developmental delay may occur

•Angioma represents failure of embryonal vessel regression

•Between 30–70% of Sturge–Weber patients have glaucoma

•About two thirds of those who have glaucoma will develop signs by 24 months of age

Mechanism

•Increased episcleral venous pressure leads to increased IOP and optic nerve damage

Clinical Findings

•Elevated IOP

•Facial hemangioma (Fig. 6.24), usually respecting midline

•Hemangioma affecting the upper eyelid is more frequently associated with elevated IOP

•Choroidal hemangioma in 40%

•Conjunctival or episcleral hemangiomas (Fig. 6.25)

•Large corneal diameter

•Photophobia

•Epiphora

•Blepharospasm

•Buphthalmos

Ancillary Testing

•Dilated fundus examination to check for choroidal hemangiomas

•Gonioscopy may show blood in Schlemm’s canal

•Skull x-ray shows classic railroad track calcifications

•Electroencephalogram to evaluate for seizures

Differential Diagnosis

• None

Treatment

•Topical hypotensive agents

•Cyclodestructive procedures

•Trabeculectomy and glaucoma drainage procedures often needed

•High risk of suprachoroidal hemorrhage with penetrating surgery

•Use of an anterior chamber maintainer and prophylactic sclerotomies during glaucoma surgery may decrease rate of suprachoroidal hemorrhage

Prognosis

•Can be difficult to manage

•Frequently fails medical management

•Trabeculotomy or goniotomy in younger patients (effective in 66% with 5-year follow-up)

•Trabeculectomy and glaucoma drainage devices

Fig. 6.24 Facial hemangioma (arrows) respecting midline.

Fig. 6.25 Prominent episcleral vessels.

Syndrome Weber–Sturge