Retinal Artery Occlusion
Central retinal artery – majority of inner retina blood circulation.
Cilioretinal artery – 15-30% of the circulation. (cilioretinal artery occlusion happens about 5% cases – watch out for GCA).
Branch retinal artery occlusion (BRAO):
40% of cases.
Retinal emboli is the cause.
Painless loss of vision – 3/4 has 6/12 vision or better.
Sectoral retinal opacification with retinal oedema.
Monitor for iris neovacularisation (rare).
Central retinal artery occlusion (CRAO):
Bilateral cases 1-2%.
Sudden painless loss of vision +/- amaurosis fugax.
Rubeosis usually within 4-5 weeks (20% cases).
Cherry red spot at fovea (cilioretinal artery patent), retinal whitening, arterial attenuation, cattle tracking (emboli), ONH oedema (think of AION).
Rule out GCA – FBC / ESR / CRP / Temporal artery biopsy / steroids Rx.
Carotid Doppler USS
Referral to TIA clinic
Young patients – hypercoagulable cause – blood test for homocysteine, sickle cell, Factor V Leiden, protein C & S, antithrombin III and antiphospholipid antibody.
Active treatment – window of 4 hours (irreversible damage after onset – retina can withstand ischaemia without damage up to 97 minutes after onset of CRAO) – ocular massage or AC paracentesis to dislodge emboli.