Varying esotropia-exotropia.

A 20-year old female was found to have an alternating pattern of right esotropia and right exotropia following surgery for a clivus chordoma three years previously. When esotropic, abduction was markedly limited while adduction was full in the right eye. When exotropic, mild limitation of both abduction and adduction was noted. Horizontal saccadic velocity studies were consistent with the diagnosis of sixth nerve palsy when esotropia was manifest and a Duane's syndrome, type II when exotropia was present. The etiology of these unusual findings is not well understood.