The earliest sign of papilledema is

Early (incipient) papilloedema:_ Symptoms are usually absent and visual acuity is normal._ Pupillary reactions are normal.Ophthalmoscopic features of early papilloedema are: (i) Obscuration of the disc margins (nasal margins are involved first followed by the superior, inferior and temporal) (ii) Blurring of peripapillary nerve fiber layer. (iii) The absence of spontaneous venous pulsation at the disc(appreciated in 80% of the normal individuals).(iv) Mild hyperemia of the disc. (v) Splinter hemorrhages in the peripapillary region may be present._ Visual fields are fairly normal.Ref: Khurana; 4th edition; Pg.No. 299