Neovascular Glaucoma
Definition
A severe secondary glaucoma caused by neovascularization of the iris and anterior chamber angle, typically driven by posterior segment ischemia from conditions such as proliferative diabetic retinopathy, central retinal vein occlusion, or ocular ischemic syndrome.
Clinical Snapshot
Neovascular glaucoma (NVG) is a severe, often refractory secondary glaucoma caused by neovascularization of the iris (rubeosis iridis) and anterior chamber angle, driven by retinal or ocular ischemia. The new vessels form a fibrovascular membrane that obstructs aqueous outflow and contracts, closing the angle. NVG is a sight-threatening emergency — IOP can reach extremely high levels, and the underlying ischemic etiology requires urgent treatment. Prognosis for vision is guarded.
Epidemiology
NVG is uncommon but devastating. The most common causes are proliferative diabetic retinopathy (PDR), central retinal vein occlusion (CRVO), and ocular ischemic syndrome (carotid artery disease). PDR and CRVO together account for approximately 90% of NVG cases.
Pathophysiology
Retinal ischemia drives upregulation of VEGF, which diffuses anteriorly and stimulates neovascularization of the iris and angle. The fibrovascular membrane initially covers the open angle (open-angle NVG with elevated IOP) and subsequently contracts, producing peripheral anterior synechiae and angle closure (closed-angle NVG). The resulting IOP elevation is often severe and refractory to medical therapy.
Risk Factors
- Proliferative diabetic retinopathy
- Central retinal vein occlusion (particularly ischemic CRVO)
- Ocular ischemic syndrome (carotid artery disease)
- Central retinal artery occlusion
- Radiation retinopathy
Clinical Presentation
Rubeosis iridis — fine neovascular tufts at the pupillary margin and on the iris surface — is the earliest sign. Patients present with severe ocular pain, markedly elevated IOP, corneal edema, and vision loss. Gonioscopy reveals neovascularization of the angle and, in advanced cases, peripheral anterior synechiae.
Diagnostic Pearls
- Examine the pupillary margin carefully at every visit in patients with PDR or ischemic CRVO — early rubeosis is subtle.
- Gonioscopy is essential — angle neovascularization may be present before visible iris neovascularization.
- NVG is a sign of severe posterior segment ischemia — urgent retinal evaluation and treatment are required.
- Anti-VEGF therapy (intravitreal) causes rapid regression of neovascularization and is the first step in management.
Differential Diagnosis
- Acute angle closure glaucoma
- Uveitic glaucoma
- Fuchs heterochromic iridocyclitis (fine vessels, but no elevated IOP)
Evidence-Based Management
Urgent anti-VEGF therapy (intravitreal bevacizumab or ranibizumab) causes rapid regression of neovascularization and is the first step. Panretinal photocoagulation (PRP) addresses the underlying retinal ischemia. IOP-lowering therapy (topical and systemic) provides symptomatic relief. Surgical intervention (tube shunt, cyclodestructive procedures) is often required for refractory IOP elevation. Cycloplegics and topical corticosteroids provide comfort.
Monitoring & Follow-Up
Urgent follow-up after anti-VEGF injection to assess neovascularization regression and IOP response. Ongoing monitoring of the underlying retinal condition.
Clinical Pearls
- Anti-VEGF therapy is the first step — it rapidly regresses neovascularization and allows subsequent surgical intervention in a more favorable eye.
- NVG is a sign of severe ischemia — the underlying cause must be identified and treated urgently.
- Prognosis is guarded — early recognition and treatment before angle closure develops offers the best chance of preserving vision.
- Screening for rubeosis in high-risk patients (ischemic CRVO, PDR) at every visit is essential for early detection.
Related Therapeutics — Clinician's Companion
- Anti-VEGF Agents — Bevacizumab, Ranibizumab (Clinician's Companion)
- Glaucoma Therapeutics (Clinician's Companion)
Key References
- 1.Havens SJ, Gulati V. Neovascular glaucoma. Dev Ophthalmol. 2016.
- 2.Shazly TA, Latina MA. Neovascular glaucoma: etiology, diagnosis and prognosis. Semin Ophthalmol. 2009.
This entry is an educational reference designed to support clinical reasoning and awareness. It does not constitute medical advice, establish a standard of care, or replace individualized patient assessment. Clinicians should consult current guidelines and applicable clinical resources when making patient care decisions.