Studies on visual evoked cortical response by liquid crystal phase difference haploscope: amblyopia and/or strabismus

Visual evoked cortical potentials induced by alternate stimulation of checkerboard pattern with the use of liquid crystal phase difference haploscope were investigated. The synchronization ratio of brain response was determined both in the group of normal binocularity and in the group with binocularity defect. The synchronization ratio of the group of normal binocularity (N = 30) is 100% at 1 Hz x 2, 98.5% +/- 3.9% at 5 Hz x 2, and 83.7% +/- 15.8% at 10 Hz x 2. On the other hand, in the group with binocularity defect, strabismus without amblyopia shows a reduction of the ratio only at the frequency of 10 Hz x 2. Anisometropic amblyopia shows a significant reduction of the ratio at 10 Hz x 2 and strabismus with amblyopia shows a remarkable reduction at 5 Hz x 2 and 10 Hz x 2. As for strabismus with or without latent binocularity, the latter cases show a significant reduction of the synchronization ratio. The reduction of synchronization ratio of VECP seems to have some relationship to the binocularity.