Head and eye movements in congenital nystagmus.

Patients with congenital nystagmus exhibit a wide range of unusual nystagmus waveforms and strategies to obtain maximum visual acuity. We investigated target acquisition strategies, head-eye coordination, and the effects of alteration of head position relative to gravity on congenital nystagmus waveforms in five patients. No changes in the nystagmus were found when patients' heads were placed in different positions relative to gravity. Two patients had distinctive abnormalities of head-eye coordination characterized both by failure of eye movement to precede head movement and by position of the eye in the orbit, after target acquisition, being in a direction opposite that of the head movement. We conclude that static changes in head position relative to gravity probably do not influence congenital nystagmus waveforms. In addition, some patients with congenital nystagmus may have abnormal head-eye coordination.