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      Drugs & Diseases > Ophthalmology

      Central Retinal Artery Occlusion (CRAO) Workup

      Updated: Nov 23, 2022
      • Author: Robert H Graham, MD; Chief Editor: Andrew G Lee, MD  more...
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      Workup

      Approach Considerations

      The risk for stroke is higher in patients with central retinal artery occlusion (CRAO). Studies have indicated that the likelihood of stroke after CRAO is up to 10 times higher during the first 3.5 years than in the regular population. This risk may continue for 10 years after the CRAO event. [23, 24]

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      Laboratory Studies

      Laboratory studies may be helpful in determining the etiology of CRAO, as follows:

      • Complete blood count (CBC) (eg, anemia, leukemia, polycythemia, platelet disorders)
      • Erythrocyte sedimentation rate (ESR) evaluation for giant cell arteritis in elderly patients
      • Hypercoagulable state evaluation (eg, factor V Leiden, prothrombin mutation, homocysteine levels, fibrinogen, antiphospholipid antibodies, prothrombin time/activated partial thromboplastin time [PT/aPTT], serum protein electrophoresis, among others)
      • Fasting blood sugar, cholesterol, triglycerides, and lipid panel to evaluate for atherosclerotic disease
      • Blood cultures to evaluate for suspected bacterial endocarditis and septic emboli
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      Imaging Studies

      Imaging studies are helpful in determining the etiology of CRAO.

      Carotid ultrasonography

      Carotid ultrasonography may be used to evaluate for atherosclerotic plaque; this appears to be more sensitive than carotid ultrasonography with Doppler, which determines only the flow.

      Magnetic resonance imaging

      Approximately 20% of patients with a CRAO also have cerebral ischemia; therefore, magnetic resonance imaging (MRI) of the brain may reveal concurrent cerebral ischemia in patients without accompanying neurologic symptoms. [25] Magnetic resonance angiography (MRA) of the head and neck may be more accurate in detecting vascular occlusive disease. Computerized tomography (CT) or computerized tomography angiography (CT/CTA) or MRI/MRA of the neck may be needed for carotid dissection.

      Fundus autofluorescence

      In the acute phase, fundus autofluorescence in ischemic areas is decreased because of retinal edema blocking the normal RPE. Eventually, this could return to normal baseline or may be associated with increased autofluorescence owing to a window defect created by the thinned-out inner retinal layers. [26]

      Fluorescein angiography

      Fluorescein angiography (see list of findings indicating CRAO below) may be a prognostic test. [27] Poor perfusion on fluorescein angiography has been associated with lower vision than exudative and mixed perfusion. [27] This finding does not influence therapy.

      • Normal choroidal filling begins 1-2 seconds before retinal filling and is complete within 5 seconds of dye appearance in healthy eyes. A delay of 5 or more seconds is seen in 10% of patients. Consider ophthalmic artery occlusion or carotid artery obstruction if choroidal filling is significantly delayed.
      • Delay in arteriovenous transit time (reference range, < 11 seconds)
      • Delay in retinal arterial filling
      • Arterial narrowing with normal fluorescein transit after recanalization

      Spectral-domain optical coherent tomography

      Spectral-domain optical coherent tomography (OCT) has been proposed as one modality that might be used to diagnose and monitor CRAO. 

      In CRAO, there is an observed increase in intensity of inner retinal layers compared with age-matched controls, and it corresponds to the layers supplied by central retinal arteries. Chen et al showed that optical intensity on OCT can be correlated with visual prognosis. [28] Incomplete CRAO shows minimal retinal architectural disruption and inner layer hyper-reflectivity without retinal edema. Subtotal CRAO demonstrated inner macular thickening and loss of organization of the inner retina, and total CRAO demonstrated marked inner retinal thickening and subfoveal choroidal thinning. [29, 30] In the chronic phase, there is a corresponding thinning of the inner retinal layers.

      Optical coherent tomography angiography

      Optical coherent tomography angiography (OCTA) is a novel noninvasive technique that eliminates the need for dye injection to evaluate the retinal microvasculature. It is based on the principle that static and nonstatic structures (ie, blood flowing through vessels) generate different signal amplitudes on repeated B scans from the same cross-sections. OCTA provides structural and functional (blood flow) information at a fixed point; however, it is not useful to appreciate leakage from vessels. [31]

      OCTA shows decreased vascular perfusion in superficial and deep retinal plexus that corresponds to poor perfusion on fluorescein angiography. In patients with the cilioretinal artery–sparing variant, the deep capillary plexus retained perfusion. However, unlike fundus fluorescein angiography, OCTA cannot demonstrate a delay in transit time. [32]

      Electroretinography

      Electroretinography shows a diminished b-wave corresponding to Muller and/or bipolar cell ischemia.

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      Other Tests

      Systemic tests are used to identify additional risks that may lead to cerebral ischemia, myocardial infarction, and cardiovascular death.

      Electrocardiography 

      Electrocardiography (ECG) is used to evaluate for possible atrial fibrillation.

      Holter monitor

      A 24-hour Holter monitor may be necessary if arrhythmia is suspected but not detected on ECG testing.

      Echocardiography 

      Echocardiography may reveal valvular disease, wall motion abnormalities, and/or mural thrombi.

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      Treatment & Management
       
       
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