All are true regarding optic neuritis except -
Electroretinogram indicates the activity of retinal (esp. rods & cones) function and has no role in assessing the functional integrity of the optic nerve. So it can't be abnormal in optic neuritis.
There is decreased visual acuity and abnormal pupillary reflex in optic neuritis. VER shows reduced amplitude and delay in transmission time.
Decreased visual acuity
Decreased pupillary reflex
Abnormal electroretinogram
Abnormal visual evoked response retinogram