Ophthalmology General 02368594 First sign of optic nerve disease is- A Papilloedema B Colour blindness C Afferent pupillary defect D Efferent pupillary defect High-Yield Explanation Marcuss Gunn pupil or RAPD (relative afferent papillary defect) is the earliest indication of optic nerve disease even in presence of normal visual acuity.