Visual Evoked Potential

[daisy.girl]

I am looking for the reference range for the results of the VEP?

[essdipity]

I have no technical info on this, but from my own testing way back when I recall that what they're looking for is delayed latency. Normal is 100, but anything up to 114 is generally in the normal range. Slower than that (meaning 115 or greater) is considered abnormal. This would indicate some obstruction in the optic nerve pathway. For MSers, a lesion.

My testing came back abnormal in right eye, though I have no eye issues whatever.

[supermum_ms]

Sorry thought i'd already posted you some VEP information, I don't have the brain cells to make sure i'm getting this right, hopefully this will help...

Latency Criteria
1. Abnormally prolonged P100 latency from any half-field response.
2. Abnormally prolonged P100 interocular half-field latency difference from either half field.
3. Abnormally prolonged P100 monocular half-field latency difference from either eye.

A monocular latency abnormality indicates a unilateral optic nerve dysfunction. Bilateral latency abnormality implies:
1. Possible bilateral prechiasmal dysfunction.
2. Possible chiasmal dysfunction if bitemporal fields are involved.
3. Possible unilateral postchiasmal dysfunction if homonymous fields are involved.

Amplitude Criteria
1. Absence of an identifiable P100, with or without the presence of the P75 and P135.
2. Abnormal interocular half-field amplitude ratio for left or right half fields.
3. Abnormal monocular half-field amplitude ratio for left or right eyes.
Because of the technical considerations of testing, half-field response amplitude ratios are generally the most variable and potentially the most misleading of test results.
Amplitude measures should only be used if repeated tests are closely reproducible and the patient has remained cooperative and alert throughout testing. The use of alternating half-field stimuli can control for much test-to-test variation.

Amplitude abnormalities are interpreted similarly to latency criteria. In addition, the absence of the P100 in the presence of the P75, N105, P135 complex suggests the involvement of central vision pathways (approximately the central 4˚ of the half field) with the preservation of peripheral vision. The absence of the P75, N 105, or P135 peaks is of uncertain significance at this time.
Low-amplitude P100 measures without significant asymmetry of amplitude ratios is of uncertain clinical significance.

Topographic and Waveform Criteria
There are currently no criteria for clinically significant abnormality of topographic or waveform changes in the presence of normal half-field response latency and amplitude measures".
https://www.acns.org/pdf/guidelines/Guideline-9B.pdf

* I understood the range to start at 85 and the maximum value for P100 to be 115 msec in patients younger than 60yr but there are known variations from lab to lab, i've seen the range mentioned being at 87-104 before so there is a lot of conflicting information out there, might be better get your ophthalmologist to go through your results and explain their normal range.

Cheers.........JJ