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
A young patient presented with sudden painless loss of vision with systolic murmur over chest, ocular examination reveals – cherry red spot in macula with clear AC, with perception of light, diagnosis – 
Select and explain. 
A. Central retinal artery occlusion, B. Central retinal vein occlusion, C. Macular choroiditis with infective endocarditis, D. Central serous retinopathy
A: Central retinal artery occlusion
Answer: A: Central retinal artery occlusion 
Explanation: Amongst the given options CRVO, CRAO and central serous retinopathy can cause sudden painless loss of vision. However following features favour the diagnosis of CRAO :-


Cherry red spot
Systolic murmur (suggests cardiac lesion which may be the source of emboli)