<prompt> Not a feature of optic neuritis:Marcus gunn pupilReduced color visionCentral scotomaLarge cup of optic nerve head  <response>: Large optic nerve head is seen in glaucoma, not in optic neuritis. Features of Optic Neuritis ON Abrupt vision loss with pain. RAPD Marcus gunn pupil Papillitis Macular star in neuroretinitis Decreased contrast sensitivity, colour vision, dark adaptation characteristic. Field defect: Swiss cheese visual fieldcentral centrocecal scotoma Delayed VER Visual Evoked Response MC systemic disorder aw Optic neuropathy is MS Multiple sclerosis 