A 55-year-old hypertensive patient presents with sudden painless monocular visual loss with 'curtain coming down from above.' Fundus shows a pale retina with a cherry red spot at fovea. The fovea is spared initially because its nutrition is supplied by:

• A Branches of the central retinal artery
• B Choriocapillaris via diffusion through Bruch's membrane
• C Perifoveal retinal capillaries from temporal arcade branches
• D Cilioretinal artery (branch of posterior ciliary circulation) ✓

Explanation

In central retinal artery occlusion (CRAO), the fovea (with its thin nerve fiber layer) may be spared if a cilioretinal artery is present (~30% of eyes). The cilioretinal artery is a branch of the posterior ciliary circulation (ophthalmic artery/short posterior ciliary arteries), not the central retinal artery, so it escapes occlusion. When present, it preserves a small island of temporal perifoveal vision. The foveal area's inner retina is normally served by the central retinal artery; the outer retina/photoreceptors at the fovea get nutrition from the choriocapillaris — but in CRAO it is the inner retinal ischemia that causes the cherry-red spot appearance.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.