A 30-year-old woman presents with sudden loss of central vision. Fundoscopy shows a cherry-red spot at the macula with a pale oedematous retina surrounding it. The cherry-red spot appears because:
- A The foveal region has no ganglion cell layer, allowing the normal underlying choroidal circulation to remain visible through the thin retina while the surrounding oedematous retina is opaque ✓
- B The macula has more RPE pigment than the peripheral retina
- C The central retinal artery has a separate macular branch that remains patent
- D Increased haemoglobin concentration in foveal capillaries makes the fovea appear red
Correct answer: A. The foveal region has no ganglion cell layer, allowing the normal underlying choroidal circulation to remain visible through the thin retina while the surrounding oedematous retina is opaque
Explanation
In central retinal artery occlusion (CRAO), the inner retina becomes oedematous and opaque from ischaemia. The foveal avascular zone has no ganglion cell layer (the ganglion cells form a single layer here vs. 8–10 layers peripherally), so the overlying retina remains thin and relatively translucent. The underlying choroidal circulation (intact, supplied by posterior ciliary arteries) shows through as a cherry-red spot against the pale ischaemic surrounding retina. This pathognomonic sign resolves as oedema clears.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.