A cause of inner retinal infarction and profound, monocular vision loss, central retinal artery occlusion (CRAO) is most commonly caused by embolic occlusion of the central retinal artery.
The most common etiological associations with occlusion of the central retinal artery include:
- carotid emboli
- cardiac emboli
- sickle cell disease
Characteristically presents with a painless, sudden onset, monocular loss of vision, which is often complete; patients often report a recent history of amaurosis fugax 4. Ophthalmoscopic examination classically reveals a "cherry red" macula surrounded by a pale retina, the former finding due to the visibility of the choroidal vasculature through the delicate macula densa.
Spectral and color flow doppler allow non-invasive examination of the retinal vasculature. Color flow Doppler is used to identify the location of the retrobulbar vessels, with subsequent pulsed wave Doppler interrogation of each flow signal. Arterial flow appears distinct from venous flow, with the following characteristics observed when interrogating the central retinal artery, distinguishing it from the adjacent central retinal vein:
- more exaggerated phasicity
- pulsatile appearance of the spectral Doppler waveform
- higher peak systolic velocity 2
- between 4.6 and 18.6 cm/second
- higher resistive index (RI)
- between 56.0 and 89.0
- calculated by taking the product of peak systolic velocity (PSV) and the difference between PSV and end-diastolic velocity (EDV)
The absence of arterial flow is consistent with central retinal artery occlusion in a suggestive clinical context. The presence of hyperechoic retrobulbar material may also be indicative of emboli occlusion when present 1.
- 1. Riccardi A, Siniscalchi C, Lerza R. Embolic Central Retinal Artery Occlusion Detected with Point-of-care Ultrasonography in the Emergency Department. (2016) The Journal of emergency medicine. 50 (4): e183-5. doi:10.1016/j.jemermed.2015.12.022 - Pubmed
- 2. Riccardi A, Siniscalchi C, Lerza R. Embolic Central Retinal Artery Occlusion Detected with Point-of-care Ultrasonography in the Emergency Department. (2016) The Journal of emergency medicine. 50 (4): e183-5. doi:10.1016/j.jemermed.2015.12.022 - Pubmed
- 3. Kilker BA, Holst JM, Hoffmann B. Bedside ocular ultrasound in the emergency department. (2014) European journal of emergency medicine : official journal of the European Society for Emergency Medicine. 21 (4): 246-53. doi:10.1097/MEJ.0000000000000070 - Pubmed
- 4. Judith E. Tintinalli, David M. Cline. Tintinalli's Emergency Medicine Manual. (2019) ISBN: 9781259009440