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
Fincham\'s test differentiates cataract from – 
Select and explain. 
A. Conjunctivitis, B. Iridocyclitis, C. Open angle Glaucoma, D. Ac. Congestive Glaucoma
D: Ac. Congestive Glaucoma
Answer: D: Ac. Congestive Glaucoma 
Explanation: The coloured halos in primary angle closure glaucoma must be differentiated from those found in acute purulent conjunctivitis and early cataractous changes :-


In conjunctivitis, the halos can be eliminated by irrigating the discharge.
The halos of glaucoma and immature cataract may be differentiated by Fincham's test in which a stenopaeic slit is passed across the pupil. During this test glaucomatous halo remains intact, while a halo due to cataract is broken up into segments.