This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
All are true regarding optic neuritis except - 
Select and explain. 
A. Decreased visual acuity, B. Decreased pupillary reflex, C. Abnormal electroretinogram, D. Abnormal visual evoked response retinogram
C: Abnormal electroretinogram
Answer: C: Abnormal electroretinogram 
Explanation: 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.