This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
Cherry red spot is seen in: September 2010 March 2013 
Select and explain. 
A. CRVO, B. CRAO, C. Eale's disease, D. Retinitis pigmentosa
B: CRAO
Answer: B: CRAO 
Explanation: Ans. B: CRAO The cherry red spot is seen in central retinal aery occlusion, appearing several hours after the blockage of the retinal aery occurs. The cherry red spot is seen because the macula receives its blood supply from the choroid aery while the surrounding retina is pale due to retinal aery infarction. It is also seen in several other conditions, classically Tay-Sachs Disease, but also in Niemarm-Pick Disease, Sandhoff disease, and mucolipidosis.