Thanks for your post about CSNB (congenital stationary night blindness) and nystagmus.
As I'm sure you know, Nystagmus occurs with lots of other conditions, mostly to do with vision, but not always. Some examples are albinism, congenital cataracts and cone/rod dystrophies.
Nystagmus can and does occur with no known cause in some cases -- I'm one example. However, it's worth emphasising that word "known". There must be a cause for every case of nystagmus, it's just that we can't always work it out -- yet.
Doctors and vision scientists have become much better at finding the underlying causes of nystagmus in recent years. The more experienced ones can now diagnose the cause in around 80 per cent of cases. But there's still a lot of work to do in unravelling the links and the whole question of cause and effect.
You would have to talk to genetic counsellors - which if I understand correctly you are doing already -- to establish whether or not you might be a carrier.