central retinal artery occlusion

what is the central retinal artery a branch of?

ophthalmic artery

what is the typical presentation of central retinal artery occlusion?

sudden, painless severe vision loss - 'descending curtain'

how much of the retina is affected by crao?

inner two-thirds

what is there a strong association with?

giant cell arteritis

is crao more common in men or women?

men

what is the most common age of onset?

> 60 y/o

what are the effects of crao on the consensual light reflex?

affected eye constricts more when light is being shone into the unaffected eye than directly into affected eye - as ischaemic retina does not sense input

what are the findings on fundoscopy?

- cherry-red spot - macula

- pale retina

why is the macula seen as a cherry-red spot?

the macula has a thinner surface, so the choroidal vasculature shows up more anyway - but this is enhanced by the pale retina

why is the retina pale?

lack of perfusion in arteries - arteries narrow and the retina becomes oedematous and opaque

what are the findings in a general exam?

- carotid bruits - from carotid atherosclerosis

- irregular pulse

- jaw claudication

what is jaw claudication?

pain and tiredness after chewing - from temporal arteritis

what are the potential causes of the embolism?

- atherosclerosis from carotid artery

- emboli from atria (from AF)

- thrombosis

- vasculitis

what are the risk factors fro crao?

- old age

- smoking

- family history

- htn, cvd etc

what condition should be tested for in crao?

giant cell arteritis

how do you test for giant cell arteritis?

ESR and temporal artery biopsy

how do you treat giant cell arteritis?

prednisolone

what is the management for CRAO?

ophthalmic emergency - irreversible retinal damage within 90 mins of onset:

1) occular massage and acetazolamide 500mg IV

2) corneal paracentesis - drain aqueous humour

3) carbogen therapy (5% CO2 and 95% O2) - hypercapnia to dislodge embolus

4) sublingual isosorbide dinitrate - vasodilate

what is the long-term management of CRAO?

aspirin