Nystagmus is a consistent wiggling of the eyes that can be due to a variety of causes. The classifications of nystagmus have improved and so has the terminology based on careful analysis of wave-forms from scientists in eye movement recording laboratories. Nystagmus limits visual acuity in at least two important ways: 1) best corrected acuity is decreased and 2) Foveation Time is diminished. Foveation Time is the percent of time the eye(s) are steadily aligned with a small target, and impacts the ability to study and read quickly. Strabismus Surgery has been proven to improve foveation and acuity and therefore is a medically needed therapy for the nystagmus form of amblyopia in younger children.
A common form of nystagmus is Infantile Nystagmus Syndrome (INS; perviously "Congenital Nystagmus") a Warning Sign that is usually detected by the infant's parents prompting confirmatory eye exam referral by the pediatrician.
Another form of nystagmus is called Fusion Maldevelopment Nystagmus Syndrome (FMNS perviously called "latent/manifest latent nystagmus") and is commonly observed in infantile esotropia or exotropia
INS: Infantile Nystagmus Syndrome (aka CN, Congenital Nystagmus)