First sign of optic nerve disease is-: (A) Papilloedema, (B) Colour blindness, (C) Afferent pupillary defect, (D) Efferent pupillary defect
Answer is C. Marcuss Gunn pupil or RAPD (relative afferent papillary defect) is the earliest indication of optic nerve disease even in presence of normal visual acuity.