This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Retina, Subject name: Ophthalmology
[{'content': 'All are true about central retinal artery occlusion (CRAO) except? \nSelect and explain. \nA. Most commonly occurs due to thromboembolism, B. Anterior chamber paracentesis is used for treatment, C. Sudden painful loss of vision, D. Occurs due to obstruction of retinal artery at the level of lamina cribrosa', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Most commonly occurs due to thromboembolism; (c) Sudden painful loss of visionRef: Kanski 7/e, p. 559, 563* Presentation is with sudden and profound loss of vision, Painless, except in Giant cell arteritis* Atherosclerosis related thrombosis at the level of lamina cribrosa is by far the most common underlying cause of CRAO, accounting for 80% cases', 'role': 'assistant'}]