An elderly diabetic presents with sudden painless loss of vision in one eye. Fundoscopy shows diffuse retinal whitening with a cherry-red spot at the fovea. The fovea retains its normal colour despite the surrounding pallor because:

• A The fovea has no photoreceptors and therefore does not swell
• B The internal limiting membrane over the fovea reflects light differently
• C The fovea receives its own direct arterial supply from the ophthalmic artery
• D The thin fovea allows the underlying choroidal circulation to show through ✓

Explanation

The findings indicate acute central retinal artery occlusion: inner retinal layers supplied by the central retinal artery become pale and opaque from ischaemic oedema. At the fovea the retina is very thin and avascular, so the red glow of the choroidal vasculature behind it shows through, producing the cherry-red spot. The fovea is densely packed with cones, it has no separate arterial supply, and the internal limiting membrane is not responsible for the colour change.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.