How do i avoid developing nystagmus?

Unlikely: Most nystagmus is congenital and deals with either defects in the central vision (such as albinos) or "wiring" defects in the ocular muscular control centers. These are developmental and cannot be avoided. Adult onset nystagmus comes about most from side effects of medications or intoxications. You can avoid these by changing the medications or the behavior.

You can't: Nystagmus usually means that the eyes are making rapid fine movements back and forth (or more rarely up and down). You are either born with it, have very poor vision (albinism), or a neurological condition (multiple sclerosis). It also can be caused by abusing some drugs. Or pouring cold water in your ear!