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': 'Methanol causes blindness by damaging following pa of the eye? \nSelect and explain. \nA. Nerve cells, B. Ganglion cells, C. Lens, D. Choroid', 'role': 'user'}, {'content': "Answer: A \nExplanation: The most common toxic cause of blindness is methanol (methyl alcohol). Formic acid is the metabolite responsible for toxicity and the metabolic acidosis that occurs with methanol poisoning. Formic acid enter the brain and ocular tissues causing central nervous system depression as well as retinal and optic nerve injury. Loss of vision may be complete and sudden within a few hours after drinking methanol or may occasionally be noted about 3 days after exposure. Pupillary reflexes are sluggish. Ophthalmoscopic examination shows swelling and hyperemia of the optic nerve head, distention of the veins, and peripapillary edema of the retina. Acute methanol poisoning causes nausea, vomiting, and abdominal pain. Ref: Smith J.C., Quan D. (2011). Chapter 179. Alcohols. In J.E. Tintinalli, J.S. Stapczynski, D.M. Cline, O.J. Ma, R.K. Cydulka, G.D. Meckler (Eds), Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7e.", 'role': 'assistant'}]