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': '0.1 to 0.2 mm nebular corneal opacity is treated by – \nSelect and explain. \nA. Penetrating keratoplasty, B. Lamellar keratoplasty, C. Enucleation, D. Evisceration', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Central nebular opacity is treated by phototherapeutic keratectomy with an excimer laser (treatment of choice) or lamellar keratoplasty.', 'role': 'assistant'}]