Convergence-evoked nystagmus. Congenital and acquired forms.

Pendular nystagmus occurring during binocualr fixation and pursuit of near objects is true convergence-evoked nystagmus. Two forms of this nystagmus are described, one congenital and the other acquired in the course of multiple sclerosis. The congenital form was conjugate and the acquired form disjunctive. Neuropathological examination provided no morphological explanation for the congenital pattern. These two unique forms of nystagmus are induced by one of the visuomotor subsystems controlling convergence.