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
Following are seen in CRA occlusion except – 
Select and explain. 
A. Gradual loss of vision, B. Headache, C. Sudden loss of vision, D. Retained central vision
A: Gradual loss of vision
Answer: A: Gradual loss of vision 
Explanation: CRAO causes sudden loss of vision (not gradual loss).
Patient with a patent cilioretinal artery may retain central vision as the macula may be spared (blood supply for the macula often derives from cilioretinal arteries).
Headache may be due to many causes, e.g. if the cause is giant cell arteritis patient may present headache, or CRAO has been reported in association with migraine attacks.