My daughter dx w/acquired nystagmus @13m.shes 20m n it seems to be going away.hardly see her eyes shake.what does this mean?will it go away completely

Likely lifelong: The nystagmus obviously has diminished in her case and hopefully the vision is good to normal. While the diminution is steady, she will probably end up with some instability which can be seen at the higher magnification with a slit lamp (a standard diagnostic instrument used by ophthalmologists). Enjoy the fact that it is hardly noticeable and hopefully the vision is good.