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': 'Cataract brunescen results due to deposition of? \nSelect and explain. \nA. Urochrome, B. Copper, C. Iron, D. Silver', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. is \'a\' i.e., Urochrome "Nuclear sclerosis also distos color vision because of - yellow -brown urochrome pigment, which accumulates in the lens and filters out blue wavelengths of ight". -- Eye pathology Older nuclear cells lose organelles and cell membranes, with increasing density and dehydration and accumulation of yellow urochrome pigment (possible photo-oxidation product). Pathology shows homogencity of nucleus , with loss of cellular lamination and increased eosinophilia. o When advanced, it becomes brown (brunescent) or black (cataracta nigra).', 'role': 'assistant'}]