What's the Best Next Step?

Clinical Focus:

• The diagnosis is Central Retinal Artery Occlusion (CRAO), an ocular analogue of an ischemic stroke and a true ophthalmologic emergency.

Aetiology/Cause:

• Embolic occlusion of the central retinal artery (a terminal branch of the ophthalmic artery), most commonly originating from ipsilateral carotid artery atheromatous plaques or cardiac valvular vegetations/mural thrombi.
• Non-embolic causes include thrombotic occlusion secondary to atherosclerosis, vasospasm, or Giant Cell Arteritis (GCA / Temporal Arteritis).
• Retinal ischemia leads to rapid, irreversible neuronal loss in inner retinal layers if perfusion is not restored within 240 minutes.

Clinical Features:

• Sudden, severe, painless, monocular vision loss ('stroke of the eye').
• History of transient monocular visual loss (amaurosis fugax) preceding the occlusion in some patients.
• Physical exam findings: profound decrease in visual acuity, positive Relative Afferent Pupillary Defect (RAPD / Marcus Gunn pupil) in the affected eye, and normal extraocular movements.

Diagnosis and Investigations: