<prompt> The cause of a coloured ;Halo; in narrow angle glaucoma isIncrease IOPCorneal oedemaLenticular changesLacrimation  <response>: Clinical Features of Glaucoma - Cupping of disc. - Raised intraocular pressure with coloured halos due to corneal oedema Ref khurana 6th edition pg 1234 - Visual field defect. 