This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ocular Trauma, Subject name: Ophthalmology
Berlin's edema is due to - 
Select and explain. 
A. Blunt trauma to eye, B. Extradural hemorrhage, C. Choroidal melanoma, D. Parsplanitis
A: Blunt trauma to eye
Answer: A: Blunt trauma to eye 
Explanation: Ans. is 'a' i.e., Blunt trauma to eye o Berlin's edema (commotio retinae) is a common condition caused by blunt injury to the eye. It is characterized by decreased vision in the injured eye a few hours after the injury. Under examination the retina appears opaque and white in colour in the periphery but the blood vessels are normally seen. Cherry-red' spot in the foveal region may be seen.