Central Retinal Artery Occlusion Flashcards
What is central retinal artery occlusion (CRAO)?
The obstruction of blood flow through the central retinal artery (rare form of ocular stroke).
It is an ophthalmic emergency.
What is the most common cause of CRAO?
Carotid artery atherosclerosis (80%)
What is the centrla retinal artery a branch of?
The ophthalmic artery (which is a branch of the internal carotid artery).
Causes of CRAO?
1) Carotid artery atherosclerosis (80%) - risk factors for CVD
2) Cardiac emboli
3) Small artery disease
4) Inflammatory disease e.g. GCA, SLE, sarcoidosis
5) Haematological disease e.g. sickle cell, APS, Factor 5 Leiden, protein S and protein C deficiency
6) Infection
What is the most common cause of CRAO in patients <40?
Cardiac emboli
Who is at risk of cardiac emboli causing CRAO?
Those with cardiac disease predisposing to embolisms such as AF, valvular disease, infection endocarditis and congenital heart disease.
What is normally the cause of CRAO in older diabetic or hypertensive patients with a normal carotid doppler?
Small artery disease i.e. local atheroma within the central retinal artery itself
Clinical features of CRAO?
Vision loss which is:
- SUDDEN onset (seconds)
- monocular
- painLESS
- severely reduced visual acuity (usually reduced to hand movements)
What may vision loss in CRAO be desscribed as?
May be described as like a ‘curtain coming down’ over vision
In 10% of patients, what may CRAO be preceded by?
Episodes of amaurosis fugax –> episodes of transient monocular visual loss
Examination findings in CRAO?
1) RAPD
2) Fundoscopy reveals a ‘cherry red’ spot at centre of macula
It is important to perform a systemic examination to look for possible causes in CRAO.
What exams should you do?
1) Carotid auscultation –> may reveal bruits indicative of turbulent flow and possible atherosclerotic disease
2) Auscultation of heart sounds –> may reveal a murmur which could indicate a possible cardiac embolism
3) Palpation of radial pulse –> may indicate AF, which is a risk factor for cardiac emboli
How is CRAO usually diagnosed?
Usually a clinical diagnosis, and investigation is typically aimed at determining the underlying cause.
What happens in a RAPD?
The pupil in the affected eye constricts more when light is shone in the OTHER eye (than when it is shone in the affected eye).
The input is not sensed by the ischaemic retina when testing the direct light reflex but is sensed during the consensual light reflex.
What will fundoscopy show in CRAO?
Pale retina with a cherry red spot.
The retina is pale due to a lack of perfusion.