Central Retinal Artery Occlusion: The Daily PANCE Blueprint
A 71-year-old man with atrial fibrillation, hypertension, and carotid disease presents 40 minutes after the sudden, painless, complete loss of vision in his right eye. He describes it as a curtain that fell and did not lift. Visual acuity in that eye is counting fingers only; the left eye is 20/25. There is a relative afferent pupillary defect on the right. The eye is white and quiet, the cornea is clear, and the intraocular pressure is normal. Funduscopy shows a diffusely pale, opacified retina with a bright red spot at the fovea and segmented, boxcar-like flow in the arterioles. Which of the following is the most likely diagnosis?
A. Central retinal vein occlusion
B. Optic neuritis
C. Acute angle-closure glaucoma
D. Central retinal artery occlusion
E. Rhegmatogenous retinal detachment
Answer and topic summary
The answer is D. Central retinal artery occlusion
Sudden, painless, profound monocular vision loss with a pale retina and a "cherry-red spot" is central retinal artery occlusion — a stroke of the eye, and it must be treated with that urgency. The retina is supplied by the central retinal artery, a branch of the ophthalmic artery off the internal carotid. When it occludes, the inner retina infarcts and becomes edematous and opaque, so the whole fundus turns pale. The fovea is the one place with no overlying inner retina; the intact choroidal circulation underneath shows straight through it, and against the surrounding white retina that normal red choroid looks like a cherry-red spot. The spot is not a lesion — it is the only healthy-looking tissue left. Boxcarring is the sludged, segmented column of blood in the arterioles. The mechanism is embolic in most cases, and the source list is the reason this diagnosis matters beyond the eye: carotid atherosclerosis, atrial fibrillation, and cardiac valvular disease. A CRAO is a completed stroke, so these patients need an immediate stroke work-up — carotid imaging, echocardiography, and rhythm monitoring — because the next embolus may go to the brain. Retinal tissue tolerates roughly 90 to 100 minutes of ischemia before irreversible loss, so the window is brutally short and outcomes are poor. Acute measures are largely low-yield but still attempted: ocular massage, anterior chamber paracentesis, and pressure-lowering agents to dislodge the embolus distally; intra-arterial thrombolysis is used at some centers within a few hours. One test you must not skip in anyone over 50: an immediate ESR and CRP to exclude giant cell arteritis, because arteritic occlusion demands high-dose steroids at once to save the fellow eye. Separating the distractors: central retinal vein occlusion gives less abrupt, less complete loss with a "blood and thunder" fundus — diffuse hemorrhages in all four quadrants, dilated tortuous veins, and disc edema; optic neuritis occurs in young adults with pain on eye movement and red desaturation and usually a normal disc; acute angle-closure glaucoma is intensely painful with a red eye, hazy cornea, mid-dilated fixed pupil, halos, nausea, and a rock-hard globe — her eye is white and the pressure is normal; and retinal detachment is preceded by flashes and floaters and shows a billowing, elevated retina rather than a uniformly pale one.
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