Examination of the fundus shows Cherry red spot in all of the following conditions, EXCEPT:
**Core Concept**
The cherry red spot is a clinical sign observed during ophthalmoscopy, where the fovea appears bright red against the pale retina. This occurs due to the relative preservation of the foveal retina in various conditions, which contrasts with the surrounding retinal areas affected by disease.
**Why the Correct Answer is Right**
The cherry red spot is typically seen in conditions where there is a loss of retinal pigment epithelium (RPE) or a reduction in melanin, such as in retinal detachment, central retinal artery occlusion, or retinal ganglion cell loss. The preservation of the foveal RPE and melanin allows the fovea to appear red in contrast to the affected surrounding retina.
**Why Each Wrong Option is Incorrect**
**Option A:** This condition would likely result in a loss of retinal pigment epithelium (RPE) and melanin, leading to a cherry red spot.
**Option B:** This condition would result in a loss of retinal ganglion cells, which could preserve the foveal RPE and melanin, leading to a cherry red spot.
**Option A:** is repeated as option A to keep the question consistent.
**Clinical Pearl / High-Yield Fact**
A cherry red spot is often associated with conditions that affect the RPE or melanin, such as retinal detachment, central retinal artery occlusion, or retinal ganglion cell loss. Remember to look for the presence or absence of a cherry red spot in the fundus examination to help diagnose these conditions.
**Correct Answer: C. Leber's Hereditary Optic Neuropathy (LHON).**