Nystagmus.

Ophthalmologic nystagmus can be congenital and manifest/latent both of whose waveforms, compensatory mechanisms, and treatment are different. Physiologically, latent nystagmus may be reversed at will, whereas nystagmus and head nodding may be simultaneously triggered at will. Occasional oscillopsia is more frequent than is usually believed; extraretinal signals may be a reason for their absence in congenital nystagmus. Astigmatism could be the consequence of nystagmus, myopia is present in most of the cases of congenital nystagmus with blocking convergence, whereas depth-of-focus anomalies are probably due to the presence of nystagmus during its critical period of development. As for treatment, botulinum toxin injection, because of its temporary effect, is not used to treat nystagmus but to help in decision-making for surgery. Four large horizontal recti recession is the last-resort surgery which may be combined with other surgical procedures and can give unexpected results. Artificial divergence surgery by contrast is one of the most valuable procedures used in congenital nystagmus.