Fincham test differentiates cataract from

The colored halos in 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.Ref: Khurana; 4th edition; Pg. 228