i had my VEP test today . When I was looking at the screen with my left eye it went all grey swirly around the outside and started coming in and found it difficult to see red square. I said its gone all fuzzy and she said I can see and made the squares bigger and it was fine. I did not have this happen on my right eye. When she finished She said there was a slight variance with my left eye but said when I really concentrated it was fine so she did not think there was a problem. She said neuro will discuss the results with me along with my MRI which I had Thursday. Now to play the waiting game again.

Has anyone had a VEP and this happen to them? Not sure if it’s normal or not.

Any responses gratefully received

Thanks in advance x

You ean like this?

Yes exactly the same! Glad it’s not just me then, she did not seem bothered by it like I say just made it bigger. What were your results? I am wondering if I shouldn’t have said anything now.


P100 wave for left eye was measured as 107; for right eye it was 98. Normally they should be no more than a couple of points different from each other, if at all and normally, depending on your age, be around 100 milliseconds (higher after age 65). A differential of 9 as in my case is at the top end of normal.

Thanks for the reply.

I see, I am 32 so there should be no more than 2 in it. Not sure what mine was as not had the results yet. She did say my left eye had a slight variance to my right but not sure what her slight variance is.

Will let you know when I do finally get my results.


Well for ‘normally’ maybe I should have said ‘typically’; remember that even a difference of 9 is just within the range for 95% or 99% of people (not sure which cutoff was being used). The other indication is how much above 100 the measurement is; the greater, the slower the rate of nerve conduction. which can indicate damage due to demyelination. I would have to look it up but I think something above 112 - 115 is probably suspicious.

Will let you know when I finally get told all my results. The consultant has my MRI and VEP results had them both since Tuesday but been told he doesn’t write the letter until on average 7-10 days after receiving the results. Although I am expecting to have to wait longer, as know what they’re like.