Ocular vascular disorders
Ischemic optic neuropathy (ION)
  • anterior (AION)
    • arteritic
    • non-arteritic
  • posterior (PION)

Central retinal vein occlusion (CRVO) → more
(the most common retinal vascular occlusive disorder)

  • non-ischemic (venous stasis retinopathy – VSR) – usually benign condition [Hayreh, 1983]
  • ischemic (hemorrhagic retinopathy – HR) – the risk of severe visual impairment

Hemi-central retinal vein occlusion (HCRVO)

  • non-ischemic (venous stasis retinopathy)
  • ischemic (hemorrhagic retinopathy)

Branch retinal vein occlusion (BRVO)

  • major BRVO
  • macular BRVO

Central retinal artery occlusion (CRAO)

  • arteritic CRAO (giant cell arteritis) – approx. 5%
  • non-arteritic permanent CRAO (NA-CRAO)
  • non-arteritic transient CRAO
  • CRAO with cilioretinal artery sparing (central vision maintained to varying degrees)

Branch retinal artery occlusion (BRAO)

  • permanent BRAO
  • transient BRAO

Cilioretinal artery occlusion

  • ophthalmic artery (OA) is the first major branch of the internal carotid artery (ICA), and it usually arises from its supraclinoid segment  Ophthalmic artery on CTA (green arrow = carotid siphon)
    •  various anomalies of OA origin have been reported  (from the cavernous segments of the ICA, MCA, PCoA, or middle meningeal artery)
    • OA diameter is  ~ 1 mm
  • OA passes through the dura and enters the orbit via the optic canal, where it runs inferolateral to the optic nerve  Ophthalmic artery (MR, transorbital TCCD)
  • the artery has numerous branches:
    • the first branch central retinal artery (CRA) arises just before the ophthalmic artery crosses over the optic nerve; it enters the lower part of the optic nerve and divides into 2 superior and 2 inferior terminal branches
      • CRA supplies the optic nerve and 6/7 layers of the retina  Branches of central retinal artery (CRA)
      • the branches do not anastomose with other arteries
    • the OA then crosses over the optic nerve to the medial side and gives off the remaining branches, which may be grouped into those supplying the orbital structures and those supplying the eye; terminal branches are the supratrochlear artery and the dorsal nasal artery
      • orbital group
        • lacrimal artery (the second and the largest branch)
        • supraorbital artery
        • posterior ethmoidal artery
        • anterior ethmoidal artery
        • internal palpebral artery
        • supratrochlear artery (frontal artery) and dorsal nasal artery (terminal branches)
      • ocular group
        • posterior ciliary arteries  (including cilioretinal artery) – pass through the sclera and supply the posterior uveal tract
          • short posterior ciliary arteries from six to twelve in number
          • long posterior ciliary arteries, two for each eye, pierce the posterior part of the sclera a short distance from the optic nerve
        • anterior ciliary artery
        • muscular branches

"DR MCLESSI" mnemonic

D = Dorsal Nasal Artery
R = [Central] Retinal Artery
M = Muscular Artery
C = Ciliary Arteries [Long / Short / Anterior]
L = Lacrimal Artery
E = Ethmoidal Arteries [Anterior / Posterior]
S = Supraorbital Artery
S = Supratrochlear Artery [Frontal]
I = Internal Palpebral Artery

Ophthalmic artery (blue arrow) and its branches (green arrow = lacrimal artery)
  • the central retinal artery (CRA) is a branch of the ophthalmic artery (OA)
  • the CRA further divides into superior and inferior branches, which eventually branch into nasal and temporal arteries
    • in ~ 50% of patients, a cilioretinal artery is present, which can adequately supply the macula even if the CRA becomes occluded
    • visual impairment depends on the extent to which the artery supplies the retina; central vision may be preserved in some cases
  • central retinal artery occlusion (CRAO) typically leads to acute retinal ischemia with optic nerve edema and necrosis of the optic nerve cells ⇒ severe and permanent visual impairment
    • significant spontaneous improvement occurs in <10% of patients
  • the incidence of CRAO is reported to be 0.85 per 100,000 people, although the actual numbers are probably higher



  • non-arteritic form
    • atherosclerosis
      • usually > 40 years of age
      • ICA stenosis present in up to 45% of CRAOs
    • cardioembolism
    • angiosclerosis
    • vasospasm
    • coagulopathy
    • polycythemia
    • glaucoma
  • non-arteritic permanent CRAO
  • non-arteritic transient CRAO
  • non-arteritic CRAO with cilioretinal sparing
  • arteritic CRAO (≤5%)

Occlusion localization

  • central retinal artery occlusion (CRAO)
    • trunk occlusion leads to complete blindness
    • exclude OA occlusion
  • branch retinal artery occlusion (BRAO)
    • occlusion of either branch results in visual field loss in the corresponding sector

Clinical presentation

  • sudden onset, painless, monocular, severe visual disturbance
    • patients with a patent cilioretinal artery may have only mild visual impairment
    • conservative therapy (without thrombolysis) improves vision in the affected eye in ~ 15% of cases
  • occlusion may be transient, presenting as a transient ischemic attack (amaurosis fugax)

Diagnostic evaluation

Ophthalmologic examination

  • clinical examination with quantification of visual impairment 
    • best corrected visual acuity (BCVA)
    • reaction to light, motion, counting fingers, etc.


  • affected part of the retina is pale; the inner retinal layer is absent in the macula, and the choroidal vasculature shines through (cherry-red spot) Cherry red spot and pale retina in CRAO
  • arteries are narrow, filiform, with interrupted blood column CRAO with interruption of flow
  • embolic material may be visible
  • ischemic retinal edema resolves within a few weeks, followed by atrophy of the retina and optic disc

Retinal fluorescein angiography (FAG) Normal fluorescein angiography (FAG) Central retinal artery occlusion on FAG Branch retinal artery occlusion on FAG

  • a technique used to examine the circulation of the retina and choroid (parts of the fundus) using a fluorescent dye and a special camera
  • detects impaired filling of retinal arteries  (delay > 11s or complete absence)
  • normal filling of choroidal arteries (complete filling within 5s)
  • consider OA occlusion if chorioretinal filling failure is detected
  • FAG can assess the effect of recanalization therapy

Electroretinography (ERG)

  • ERG is a test that measures the electrical activity of the retina and can be used to diagnose CRAO and assess the severity of the condition
  • electrodes are placed on the cornea of the eye, and these electrodes record the electrical signals generated by the retina in response to light stimuli

Etiologic evaluation

Blood tests (vascular risk factors)

  • CBC, coagulation tests
  • erythrocyte sedimentation rate (ESR), CRP
  • ionogram, lipid panel, glycemia
  • blood cultures (if endocarditis is suspected)

Vascular imaging


  • MR-DWI is the best method to exclude clinically silent brain infarcts
  • it is better to perform brain CT or MRI (according to local stroke protocol) prior to IVT administration

Other tests


  • spontaneous improvement is rare (< 10-15% of CRAOs)
  • none of the conservative treatments (antiplatelet agents, intraocular pressure reduction, vasodilators, eye massage, hemodilution, steroids, heparin) have been proven effective; their use is based on case reports and small series of patients
  • intravenous thrombolysis has become the standard of care in eligible patients
  • a fundoscopic examination is essential before starting therapy to confirm the diagnosis and to exclude, e.g., intraocular hemorrhage. If arteritis is suspected, ESR and CRP should be obtained (safety of thrombolysis in the arteritic form of CRAO is unknown; in addition, immediate corticotherapy is indicated to prevent occlusion in the fellow eye)
  • therapeutic window
    • experimental data indicate that retinal cells survive for ~ 120-240 minutes in the presence of complete ischemia
    • even with CRA occlusion, complete ischemia rarely occurs; therefore, an interval of 0-12 hours is often used

Conservative treatment

Methods are usually combined, the effect is uncertain, trials have shown no effect compared to placebo [Fraser, 2009]

  • mechanical dislodgement of the embolus (repeated bulb massage/ compression)
  • vasodilation (IV pentoxifylline, sublingual isosorbide dinitrate)
  • intraocular pressure reduction (to increase perfusion pressure in the CRA)
    • acetazolamide 500mg IV or PO
    • short-term IV mannitol
    • methylprednisolone
    • anterior chamber paracentesis
  • increase blood O2
    • oxygen therapy or hyperbaric oxygen therapy (HBOT) within 2-12 hours of onset

Intravenous thrombolysis

  • early thrombolysis is more effective than conservative therapy, but randomized trials are lacking [Grory, 2020]
  • the therapeutic window is at least 4.5 hours  (AHA guidelines 2021) [Grory, 2021]
    • one meta-analysis demonstrated safety and efficacy within 4.5 hours [Dumitrascu, 2017]
    • “time is retina” – IVT administered within 6.5 has better outcomes than IVT administered in the 6.5-12 hour window [Biousse, 2010] [Hattenbach, 2008]
    • the EAGLE trial with a therapeutic window of 20 hours failed to show benefit of IVT
  • verify the visual impairment and contraindications to thrombolysis before administering thrombolysis (weigh risk-benefit)
  • it is safer to perform brain imaging in all CRAO cases before thrombolysis (to rule out subacute clinically silent ischemia)

 → Intravenous thrombolysis

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Intraarterial thrombolysis

  • tPA is usually injected into the ophthalmic artery
  • intraarterial tPA dosage is not standardized (ACTILYSE 15-50mg) (AHA guidelines 2021)
  • effect of IAT has been reported when started in less than 15 hours

Secondary prevention

  • investigate etiology ASAP ⇒ start individualized stroke prevention (the same as for other types of stroke → Stroke prevention)
    • always rule out carotid stenosis, as early CEA may significantly reduce the risk of recurrent stroke

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Central retinal artery occlusion (CRAO)
link: https://www.stroke-manual.com/central-retinal-artery-occlusion-crao/