Hi and welcome,
I'm not sure if you intended for your question to land in the MS community or not but MS as an explanation, would be less likely in comparison to any of the other much more common visual conditions in young children.
I would suggest getting the second opinion or the opinion of a paediatric ophthalmologist if the ophthalmologist isn't able to work it out or explain what this could mean.....
Cheers......JJ
There are only two eye conditions in MS. Optic Neuritis which the eye doctor would have seen with the perepheral or the MRI would pick up or double vision. Both are neurological He should have seen evidence of either. An eeg would show nothing. A VEP would help if it were neurological.
You could always see a Neuro opthalmologist if you think it is neurological.
Alex