[Functional study in early strabismus: translucent screens and electro-nystagmography].

Abstract

The symptoms of infantile strabismus are triggered by fixation, chiefly monocular fixation. On the excluded eye, "occlusion deviations" (elevation, esodeviation, extorsion) are well observed through a "translucent" unilateral cover. These deviations are super-imposed upon a position of rest without fixation which may be an orthoposition, well observed through bilateral translucent occluders. They are caused by a rupture of binocular retinal stimuli which does not mean rupture of fusion (ex: the darkening Bielschowsky test). Electro-oculographic studies confirm the prevalence of adduction during fixation (nystagmus, pursuit, optokinetic nystagmus). This directional asymmetry is typical of the infant's immature system of fixation. In infantile strabismus, it persists because of missing binocular links (corpus callosum--cortex----midbrain) as shown by the study of the so-called congenital monophthalm syndrome (unilateral congenital blindness).