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
[{'content': 'Dellen is – \nSelect and explain. \nA. Localized thinning of peripheral cornea, B. Raised lesions in corneo limbal junction, C. Age related macular degeneration, D. Marginal keratitis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Dellen are localized areas of thinning or drying, of the peripheral cornea, usually on temporal side.', 'role': 'assistant'}]