eMedicine Specialties > Ophthalmology > Intraocular Pressure

Glaucoma, Neovascular

Author: Yasser A Khan, MD, Consulting Staff, Credit Valley Eye Care
Coauthor(s): Iqbal Ike K Ahmed, MD, FRCSC, Clinical Assistant Professor, Department of Ophthalmology, University of Utah; Khalid Hasanee, MD, Glaucoma and Anterior Segment Fellow, Department of Ophthalmology, University of Toronto; Baseer U Khan, MD, Staff Physician, Department of Ophthalmology, University of Toronto, Canada
Contributor Information and Disclosures

Updated: Jun 26, 2006

Introduction

Background

Neovascular glaucoma (NVG) is classified as a secondary glaucoma. First documented in 1871, historically, it has been referred to as hemorrhagic glaucoma, thrombotic glaucoma, congestive glaucoma, rubeotic glaucoma, and diabetic hemorrhagic glaucoma. Numerous secondary ocular and systemic diseases that share one common element, retinal ischemia/hypoxia and subsequent release of an angiogenesis factor, cause NVG. This angiogenesis factor causes new blood vessel growth from preexisting vascular structure. Depending on the progression of NVG, it can cause glaucoma either through secondary open-angle or secondary closed-angle mechanisms. This is accomplished through the growth of a fibrovascular membrane over the trabecular meshwork in the anterior chamber angle, resulting in obstruction of the meshwork and/or associated peripheral anterior synechiae.

NVG is a potentially devastating glaucoma, where delayed diagnosis or poor management can result in complete loss of vision or, quite possibly, loss of the globe itself. Early diagnosis of the disease, followed by immediate and aggressive treatment, is imperative. In managing NVG, it is essential to treat both the elevated intraocular pressure (IOP) and the underlying cause of the disease.

Pathophysiology

Retinal ischemia is the most common and important mechanism in most, if not all, cases that result in the anterior segment changes causing NVG. Various predisposing conditions cause retinal hypoxia and, consequently, production of an angiogenesis factor.

Several angiogenesis factors have been identified as potential agents causing ocular neovascularization. Recent studies suggest that vascular endothelial growth factor (VEGF) might play a central role in angiogenesis.

Once released, the angiogenic factor(s) diffuses into the aqueous and the anterior segment and interacts with vascular structures in areas where the greatest aqueous-tissue contact occurs. The resultant growth of new vessels at the pupillary border and iris surface (neovascularization of the iris [NVI]) and over the iris angle (neovascularization of the angle [NVA]) ultimately leads to formation of fibrovascular membranes. The fibrovascular membranes, which may be invisible on gonioscopy, accompany NVA and progressively obstruct the trabecular meshwork. This causes secondary open-angle glaucoma.

As the disease process continues, the fibrovascular membranes along the NVA tend to mature and contract, thereby tenting the iris toward the trabecular meshwork and resulting in peripheral anterior synechiae and progressive synechial angle closure. Elevated IOP is a direct result of this secondary angle-closure glaucoma.

Frequency

United States

Incidence of NVG is rare.

Mortality/Morbidity

Treatment of NVG is difficult. Maintaining visual acuity in patients with NVG also is difficult.

Age

NVG is more prevalent in elderly patients.

Clinical

History

A careful and detailed ocular and systemic history is imperative in diagnosing both NVG and the underlying problem causing it.

Physical

A complete ocular examination of both eyes, particularly of the posterior segment, will almost certainly provide the etiology of neovascularization. Of the 3 most common causes of NVG, ocular ischemic syndrome presents as a diagnostic dilemma and, thus, deserves special mention.

The typical clinical presentation of NVG is the same regardless of the underlying cause. The typical clinical presentation can be divided into the following 2 stages: the early stage and the advanced stage. These stages generally follow each other in progression, and the early stage is subdivided further into rubeosis iridis and secondary open-angle glaucoma.

• Early stage (rubeosis iridis)
  • Normal IOP
  • Presence of tiny, neovascular, dilated capillary tufts at pupillary margin
  • High magnification on slit lamp (to view earliest finding in NVG)
  • NVI (irregular, nonradial vessels usually not in the iris stroma)
  • NVA (can occur with or without NVI)
  • Careful gonioscopy in all eyes at high risk for NVG even without pupillary and iris involvement
  • Poorly reactive pupil
  • Ectropion uvea
• Early stage (secondary open-angle glaucoma)
  • Elevated IOP
  • NVI continuous with NVA
  • Proliferation of neovascular tissue over the angle
  • Fibrovascular membranes (develop circumferentially across the angle, blocking the trabecular meshwork)
• Advanced stage: In this stage, secondary angle-closure glaucoma is characterized by some or all of the following:
  • Acute severe pain, headache, nausea, and/or vomiting
  • Photophobia
  • Reduced visual acuity (counting fingers to hand motion)
  • Elevated IOP (¡Ý60 mm Hg)
  • Conjunctival injection
  • Corneal edema
  • Plus/minus hyphema
  • Aqueous flare
  • Synechial angle closure
  • Severe rubeosis
  • Distorted, fixed, mid-dilated pupil and ectropion uveae
  • Retinal neovascularization and/or hemorrhage
  • Optic nerve cupping (possibly)
• Ocular ischemic syndrome
  • Ocular ischemic syndrome occurs in the presence of more than 90% of patients with carotid artery stenosis, but it can occur as a result of aortic arch disease (eg, syphilis, Takayasu arteritis, dissecting aneurysm), in which case the presentation may be bilateral.
  • Symptoms include a dull periocular/periorbital pain that can be secondary to the ischemia and/or NVG.
  • Signs include the following:
    • Vision can vary from 20/20 to no light perception.
    • Midperipheral intraretinal hemorrhage (in contrast to diabetic retinopathy and CRVO where the hemorrhage is mostly situated in the posterior pole)
    • IOP can be elevated secondary to NVG, decreased secondary to ciliary body hypoperfusion, or normal as a result of both processes.
    • Other signs include corneal decompensation, iritis, iris atrophy, cataract, and spontaneous pulsations of the central retinal artery.
    • Intravenous fluorescein angiogram will demonstrate prolonged choroidal filling and increased arteriovenous transit time.

Causes

• Relatively frequent causes of NVG include the following:
  • Central retinal vein occlusion (CRVO)
  • Proliferative diabetic retinopathy
  • Carotid artery occlusive disease (CAOD)
• Less frequent causes of NVG include the following:
  • Branch retinal vein occlusion
  • Central retinal artery occlusion (CRAO)
  • Intraocular tumor
  • Chronic retinal detachment
  • Secondary to intraocular lens (uveitis-glaucoma-hyphema [UGH] syndrome)
  • Chronic or severe ocular inflammation
  • Endophthalmitis
  • Sickle cell retinopathy
  • Retinopathy of prematurity
  • Radiation retinopathy
  • Eales disease
  • Coats disease
  • Carotid-cavernous fistula
  • Ocular ischemic syndrome/carotid insufficiency
  • Takayasu disease
  • Giant cell arteritis
  • Anterior segment ischemia (ie, previous extraocular muscle surgery)
  • Trauma

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