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  • the central retinal artery (CRA) is a branch of the ophthalmic artery (OA)
  • CRA divides into upper and lower branches, which are further divided into nasal and temporal branches
    • in approx. 50% of patients, a cilioretinal artery is present, which sufficiently supplies the macula even in case of CRAO !!
    • visual impairment depends on the extent to which the artery supplies the retina; central vision may be preserved
  • occlusion of the CRA 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 happens < 10% of patients
  • incidence is reported as 0.85/100,000, but the actual incidence is probably higher

Etiopathogenesis

Etiology

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Localization of the occlusion

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

Clinical presentation

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

Diagnostic evaluation

Ophthalmologic examination

  • clinical examination with quantification of the visual impairment 
    • best-corrected visual acuity (BCVA)
    • reaction to light, movement, finger counting, etc.

Ophthalmoscopy

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

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

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

Electroretinography (ERG)

Etiologic evaluation

  • rule out the arteritic form !!! (→ temporal arteritis)
  • investigate vascular risk factors and exclude significant ICA stenosis (present in up to 30% of cases)

Blood tests (vascular risk factors)

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

Vessel imaging

  • neurosonology / MRA / CTA
  • exclude extra-intracranial ICA stenosis  Carotid artery stenosis (ultrasound, CTA, MRA, DSA)

Neuroimaging

  • MR DWI is the best method to rule out clinically silent infarctions
  • prior IVT administration, it is better to perform brain CT or MRI (according to local stroke protocol)

Other examinations

  • ECG
  • echocardiography (TTE+TEE)
  • TCCD bubble test

Management

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

Methods are usually combined, the effect is uncertain, studies have not shown an effect compared to placebo [Fraser, 2009]

  • attempt to mechanically release the embolus (repeated massage/bulb compression)
  • vasodilation (pentoxifylline i.v., isosorbide dinitrate sublingually)
  • intraocular pressure reduction (attempt to increase perfusion pressure in the CRA)
    • acetazolamide 500mg i.v. or po.
    • short-term Mannitol i.v.
    • Solumedrol
    • anterior chamber paracentesis
  • increase in blood O2 content
    • oxygen therapy or hyperbaric oxygen therapy – HBOT (within 2-12h from onset)
Intravenous thrombolysis
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Intraarterial thrombolysis
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Secondary prevention
  • investigate the etiology ASAP ⇒ start customized stroke prevention (the same as in other types of stroke → see here)
    • always rule out carotid stenosis because early CEA may significantly reduce the risk of recurrent stroke
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