What is central retinal artery occlusion?

• A. Painful red eye with discharge.
• B. Gradual improvement in vision with floaters.
• C. Sudden, painless, complete monocular vision loss with a 'cherry-red spot' on fundus.
• D. Diplopia with normal fundus.

Answer: (C)

Central retinal artery occlusion presents as a sudden, painless loss of vision in one eye due to abrupt blockage of the blood supply to the retina. The hallmark finding on eye exam is a pale retina with a cherry-red spot at the fovea. The cherry-red spot occurs because the fovea is thin and the underlying choroidal circulation shows through, while the surrounding ischemic retina becomes pale. This combination—sudden, painless monocular vision loss with that distinct fundoscopic appearance—is characteristic of CRAO.

Other scenarios don’t fit as well: a painful red eye with discharge points to infectious or inflammatory eye conditions rather than an abrupt arterial occlusion; gradual improvement in vision with floaters suggests retinal detachment or vitreous changes rather than an acute vascular occlusion; diplopia with a normal fundus implies a cranial nerve or extraocular muscle issue rather than retinal ischemia.

CRAO is an ophthalmic emergency because it reflects possible systemic embolic or thrombotic disease, so urgent evaluation and management are essential.