In central retinal artery occlusion (CRAO), the 'cherry red spot' at the macula occurs because:

• A Increased lipofuscin deposition in the macula causes orange discoloration
• B Macular vessels are supplied by the choroidal circulation via the choriocapillaris and thus retain perfusion, contrasting with the white ischemic surrounding retina ✓
• C Macular pigment (lutein/zeaxanthin) absorbs light differently from the surrounding pale retina
• D The foveola lacks ganglion cell layer, allowing direct visualization of RPE vasculature

Explanation

In CRAO, the entire inner retina becomes ischemic and edematous, appearing opaque/white due to intracellular swelling of ganglion cell layer neurons. However, the foveal/macular region receives its outer retinal nutrition from the choriocapillaris (choroidal circulation), which is unaffected by CRAO. The thin foveal retina (nearly devoid of ganglion cell layer) remains transparent, allowing the normal orange-red color of the underlying choroidal vasculature to be seen through it — creating the cherry-red spot appearance. The contrast between the red macula and surrounding white ischemic retina is pathognomonic.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.