Pendular and See-saw Nystagmus in Four Patients with Achiasma

Congenital achiasma is a rare disorder characterized by severe or total absence of crossing fibers at the optic chiasm. This disorder typically occurs in isolation, but can also be associated with septo-optic dysplasia, esophageal atresia, agenesis of the corpus callosum, and VACTERL (vertebral defects, anal atresia, cardiac defects, tracheoesophageal fistula with atresia, renal defects, and limb defects). Previously reported, achiasma patients have see-saw nystagmus (SSN) and horizontal pendular nystagmus described as "congenital nystagmus". See-saw nystagmus can also be observed in head trauma, sellar mass lesions, cone-rod dystrophy, septo-optic dysplasia, and agenesis of the corpus callosum.