Nystagmus
A child with nystagmus presents a continuous rhythmic movement of the eyes (the direction of movement differs from child to child), while sometimes eye movements may also be accompanied by respective rhythmic movements of the head.
Nystagmus may be congenital (when it appears in the first months of life), or acquired (when it first appears later).
The causes may be ocular (e.g. albinism, optic nerve hypoplasia, congenital cataract, retinal dystrophies, etc.), or neurologic (e.g. multiple sclerosis, syndromes, metabolic conditions, etc.).
All children with nystagmus should be thoroughly examined by a pediatric ophthalmologist and pediatrician, in order to identify the cause of the nystagmus. In cases of acquired nystagmus, the child should also be examined by a pediatric neurologist.
Many children with nystagmus manage to decrease the scope of eye movements, by adopting a specific head and eye/gaze position (torticollis). They see more clearly from that position, and they prefer it so as to see details.

In general, children with nystagmus can see better at short distances rather than at long distances, and glasses usually do not help.
Nystagmus does not subside by itself, and children should be monitored for potential developments regarding their eyesight.
Specially-made glasses with prisms or surgical interventions are recommended only in special cases.