Which among the following is the indication for using Fincham's test?

The coloured 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 stenopaic 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: Comprehensive Ophthalmology by AK Khurana, 4th edition, Page 228.