ItCarlow
I doubt if you will find much information about nystagmus on this site - it's a rare condition, and not many people know of it.
HOWEVER, I'm a fellow sufferer, so can empathise with you.
I know it is not an automatic ban to a medical certificate, (I have a class 2 and am going to try for a class 1). As far as the military, however, I don't know.
As I said, this condition is unusual, so if you want me to share my experiences of it with you, (plus some possible help - ), post again, and I'll email you in the next few days
FD