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Neovascular Glaucoma

URGENT — Glaucoma

Symptoms

Presentation

  • Often asymptomatic in early stages.
  • Severe ocular pain and frontal headache (in late stages).
  • Diffuse ocular redness and photophobia.
  • Profoundly decreased vision.

Clinical Findings

Iris and angle

  • Neovascularization of the iris (NVI): Earliest visible sign typically at the pupillary margin.
  • Neovascularization of the angle (NVA) on gonioscopy.
  • Ectropion uveae (eversion of the pupillary margin pigment).
  • Peripheral anterior synechiae (PAS) and progressive, irreversible "zippering" angle closure (late).

Anterior segment

  • Mild anterior chamber cell and flare.
  • Conjunctival injection.
  • Microcystic corneal edema (with acute IOP rise).
  • Spontaneous hyphema.

Posterior segment

  • Glaucomatous optic nerve cupping.
  • Visual field loss characteristic of severe glaucoma.

Etiology

Pathophysiology

  • Retinal ischemia → VEGF release → Iris/angle neovascularization → Fibrovascular angle closure.

Common causes

  • Proliferative Diabetic Retinopathy (PDR).
  • Ischemic Central Retinal Vein Occlusion (CRVO; classic "90-day glaucoma").
  • Ocular Ischemic Syndrome (OIS; secondary to severe carotid occlusive disease).
  • Central Retinal Artery Occlusion (CRAO).

Other causes

  • BRVO/BRAO, chronic uveitis, chronic retinal detachment, intraocular tumors, trauma, or previous radiation.

Red Flags

  • Rubeosis iridis: Angle closure can develop aggressively within weeks of onset.
  • Systemic etiology: Underlying causes like PDR, ischemic CRVO, and OIS require urgent systemic investigation.
  • Pain + IOP >40 mmHg + corneal edema strongly suggests a poor long-term visual prognosis.
  • Treating the IOP medically without treating the underlying ischemia (via PRP) is completely futile.

Investigations

Ocular examination

  • Applanation IOP measurement and meticulous gonioscopy (assess directly for NVA and PAS extent).
  • Dilated fundus exam to identify the primary etiology and assess the optic nerve.

Imaging

  • Fluorescein Angiography (FA) to identify areas of profound retinal ischemia and guide targeted PRP.
  • B-scan ultrasound if the ocular media is opaque (e.g., dense cataract or vitreous hemorrhage) to rule out an underlying tumor or retinal detachment.

Systemic workup

  • Carotid Doppler ultrasound if no direct retinal etiology is found (mandatory to rule out OIS).

Treatment

Medical management

  • IOP reduction: Topical beta-blockers, alpha-2 agonists, and CAIs (± systemic oral/IV acetazolamide).
  • Inflammation and pain control: Topical prednisolone acetate 1% and cycloplegics (atropine 1%).
  • Osmotics: IV mannitol for refractory emergent IOP spikes.

Ischemia treatment

  • Panretinal Photocoagulation (PRP): The definitive, permanent treatment to eliminate the hypoxic VEGF source.
  • Intravitreal anti-VEGF (e.g., bevacizumab): Rapid temporary regression of NVI/NVA; acts strictly as a bridge to PRP or surgery.

Surgical options

  • Glaucoma Drainage Device (Ahmed/Baerveldt tube shunts): The overwhelmingly preferred surgical option.
  • Cyclophotocoagulation (CPC): Reserved for pain control in blind, painful eyes or eyes with extremely poor visual potential.
  • Trabeculectomy: Carries a high failure rate; considered only once the neovascularization is proven to be completely inactive.

Clinical Pearl

Neovascular glaucoma is a devastating end-stage of retinal ischemia. NVI at the pupillary margin is the earliest visible sign. The "90-day rule" after ischemic CRVO: NVI develops in ~33% without treatment. Intravitreal anti-VEGF rapidly reverses rubeosis — but it is never a standalone treatment. The golden rule: Anti-VEGF buys you time, PRP buys you a cure. Always stage the angle: Stages 1–2 (open angle) are the reversible window where aggressive PRP can restore normal outflow; Stage 3 (PAS closure) is largely irreversible and strictly requires a tube shunt or CPC.

Differential Diagnosis

  • • Severe inflammatory/uveitic glaucoma.
  • • Primary acute angle-closure glaucoma.
  • • Rubeosis iridis (without secondary glaucoma).

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