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Central Retinal Vein Occlusion

CRITICAL — Retina

Symptoms

Painless vision loss (typically unilateral).

Clinical Findings

Acute fundus appearance

  • "Blood and thunder" fundus: diffuse retinal hemorrhages in all four quadrants.
  • Dilated and tortuous retinal veins.
  • Optic disc edema and hemorrhages.
  • Macular edema (ME).

Late signs

  • Optociliary collateral vessels on the disc (shunting blood from retinal to choroidal circulation).
  • Neovascularization: NVI (iris), NVA (angle), NVD (disc), NVE (elsewhere).

Subtypes

  • Ischemic CRVO: VA <20/200, significant RAPD, and extensive capillary nonperfusion (>10 disc diameters on IVFA).
  • Non-ischemic CRVO: VA often >20/200, mild/absent RAPD, and less severe fundus changes; 10% convert to ischemic.

Etiology

Mechanism

  • Central retinal artery (CRA) atherosclerosis compresses the adjacent vein at the lamina cribrosa, leading to thrombosis.

Systemic risk factors

  • Hypertension (HTN) is the most common association.
  • Diabetes mellitus, hyperlipidemia, and glaucoma.
  • Medications: oral contraceptives, diuretics.

Hypercoagulable & inflammatory

  • Young patients (<50): Factor V Leiden, Protein C/S deficiency, Antiphospholipid syndrome.
  • Hyperviscosity: multiple myeloma, polycythemia, Waldenström macroglobulinemia.
  • Vasculitis: Sarcoidosis, syphilis, SLE.

Orbital compression

  • Thyroid eye disease, orbital tumors, or AV fistulas.

Red Flags

Ischemic CRVO → high risk of "90-day glaucoma" (neovascular glaucoma); requires monthly gonioscopy.

Anterior segment neovascularization (NVI/NVA) → mandates immediate PRP and/or anti-VEGF.

Bilateral or young patient (<50) → requires comprehensive hypercoagulable and hyperviscosity workup.

Vision <20/400 with cotton-wool spots → highly suspicious for the ischemic variant.

Investigations

Ocular exam

  • Gonioscopy BEFORE dilation: essential to rule out NVI and NVA.
  • Dilated fundus examination and IOP measurement.

Imaging

  • OCT: baseline and serial monitoring for macular edema.
  • IVFA: evaluate for capillary nonperfusion to risk-stratify neovascular potential.

Systemic workup

  • Blood pressure, fasting glucose, HbA1c, CBC, PT/PTT, and lipid profile.
  • Target workup for young/bilateral cases: Hemoglobin electrophoresis, ANA, RPR/FTA-ABS, Protein C/S, Factor V Leiden, and Homocysteine.

Treatment

Macular edema (ME)

  • Anti-VEGF (Standard of Care): ranibizumab, aflibercept, or bevacizumab.
  • Intravitreal Steroids: Dexamethasone implant (Ozurdex) or triamcinolone (risks: cataract, high IOP).

Neovascularization (NV)

  • Panretinal Photocoagulation (PRP): indicated promptly if NVI or NVA is detected.
  • Anti-VEGF: useful adjunct to PRP for rapid regression of neovascular vessels.

Systemic optimization

  • Manage underlying HTN, DM, and hyperlipidemia.
  • Discontinue oral contraceptives; consider alternatives to diuretics.
  • Aspirin 81–325 mg: commonly used but efficacy is unproven and may increase hemorrhage.

Clinical Pearl

In patients under 45, CRVO is a "hypercoagulable workup" until proven otherwise. For ischemic cases, remember the high risk of neovascular glaucoma within the first 90 days.

Differential Diagnosis

  • Ocular Ischemic Syndrome (OIS)
  • Branch Retinal Vein Occlusion (BRVO)
  • Diabetic Retinopathy
  • Hypertensive Retinopathy
  • Hyperviscosity Syndrome

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