For examination of horizontal optokinetic nystagmus a large cylinder (2m in diameter and 2m in height) was rotated electrically both right and left with an angular acceleration of 2°/sec2 for 90 seconds. Tests were carried out by binocular and monocular vision.
Results are as follows :
(1) In a patient with strabismus convergens et sursum vergens, nystagmus was well evoked by optokinetic stimuli to both right and left in the case of binocular vision. In monocular vision, when the cylinder was rotated from the side of open eye to that of the covered, nystagmus was induced; on the other hand, while the cylinder was rotated from the side of covered eye to that of the open, provocation of nystagmus was disturbed. Namely, monocular unidirectionality of optokinetic reflex was observed. Taking into account the work of Tokita (1956) and Guillery (1969), this abnormality may suggest the disorder of uncrossed fibers in the optic tract.
(2) In a patient with strabismus convergens et alternans, on the occasion of monocular vision, when the right eye was stimulated, movement of the left was disturbed; on the other hand, when left eye was stimulated, that of the right was disturbed. This abnormality suggests a disorder of association between the right and left eye system.
(3) In a patient with strabismus divergens, movement of the right eye did not occur in the same manner as that of the left. Accordingly, conjugate eye-movement was disturbed.
(4) In a patient with strabismus convergens, smooth pursuit of a moving object was disturbed. This abnormality suggests a disorder in the occipital lobe.
Various optokinetic abnormalities are observed in patients with strabismus and include : Optokinetic monocular unidirectionality, disorder of association between the right and left eye system, disturbance of conjugate eye-movement and disorder of smooth pursuit of a moving object.
