OP9.3 | Retinal Vascular Occlusions — Summary & Reflection

KEY TAKEAWAYS

Retinal vascular occlusions comprise four entities — CRAO, BRAO, CRVO, and BRVO — each with a characteristic fundoscopic appearance and management priority. CRAO is a true ocular emergency: sudden, complete, painless monocular visual loss with a pale retina and cherry-red spot; treatment must begin within 90 minutes (ocular massage, IOP reduction, AC paracentesis). Always exclude giant cell arteritis (elevated ESR/CRP) in patients over 50 — treat with immediate high-dose steroids. Investigate all arterial occlusions for embolic source (carotid Doppler, echo, cardiac rhythm). BRAO produces a segmental pale retinal sector with partial field loss. CRVO produces the 'blood-and-thunder' fundus (4-quadrant flame haemorrhages, tortuous veins, disc oedema) and is classified into ischaemic (RAPD present, VA severely reduced, >10 disc areas non-perfusion on FFA, ~30% rubeosis risk) and non-ischaemic (better prognosis). CRVO macular oedema is treated with intravitreal anti-VEGF (ranibizumab/aflibercept — CRUISE trial). Ischaemic CRVO requires monthly monitoring for rubeosis iridis → urgent PRP and IOP management if it develops. BRVO is the commonest, most commonly superotemporal, associated with hypertension and AV nipping; treat macular oedema with anti-VEGF (BRAVO trial). Systemic risk factor control — especially BP — is essential in all venous occlusions.

REFLECT

Reflect on the following:
- CRAO is often compared to a stroke. In what ways is the pathophysiology similar? In what ways does the eye's unique anatomy (the dual retinal/choroidal supply, the cherry-red spot) make it different from a pure cortical stroke?
- If a patient presents to your clinic 4 hours after CRAO onset, the therapeutic window has passed. How would you counsel this patient about what happened, what the prognosis is, and what must be done now to protect the other eye and prevent a brain stroke?
- Consider why the superotemporal branch is the most common site of BRVO. What anatomical explanation makes this site particularly vulnerable? (Think about arteriovenous crossing anatomy.)
- The distinction between ischaemic and non-ischaemic CRVO is clinically important. If you had to examine a CRVO patient in a clinic without access to FFA, what two bedside clinical features would you use to classify the occlusion as likely ischaemic?