This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Techniques of Ocular Examination and Diagnostic Tests, Subject name: Ophthalmology
[{'content': 'Fincham test is used for - \nSelect and explain. \nA. Differentiating open angle from angle closure glaucoma, B. Differentiate halos due to angle closure glaucoma and immature cataract, C. Classify glaucomatous optic atrophy, D. Differentate granulomatous and non granulomatous uveitis', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e. Differentiate halos due to angle closure glaucoma and immature cataract Fincham'stesto 'Fincham's test is used to differentiate the halos of PACG and immature cataract. In this a stenopaeic slit is passed across the pupil - Glaucomatous halo remains intact, while a halo due to cataract is broken up into segments.", 'role': 'assistant'}]