INDEPENDENCE OF OPTOKINETIC NYSTAGMUS ASYMMETRY AND BINOCULARITY IN INFANTILE ESOTROPIA

Objective: Children with congenital esotropia, amblyopia, or early vis ual deprivation have persistent asymmetric monocular pursuit, as measu red by optokinetic nystagmus (OKN), and favor targets moving in a temp oral to nasal direction. Previous studies suggest that binocular visua l development is necessary for the development of symmetric monocular OKN. We recently treated patients with congenital esotropia with uncon ventionally early surgery to establish good binocularity. We wished to determine if mature symmetric OKN responses could develop in patients with congenital esotropia following the acquisition of good stereopsi s. Methods: Electro-oculographic recordings documented horizontal eye movements in response to an electronic OKN stimulus. Patients: The rec ordings of three patients with congenital esotropia that had been surg ically aligned before age 20 weeks and who had achieved high-grade ste reopsis with random dot and Titmus stereographic testing were studied. We compared this group of children with groups of age-matched control s, including the following: (1) three patients with congenital esotrop ia who underwent surgical alignment after age 6 months and who had no amblyopia bur poor stereopsis; (2) three children with accommodative e sotropia, good ocular alignment when wearing spectacles, and good ster eopsis; and (3) three normal children. Results: The normal children an d those with accommodative esotropia demonstrated normal symmetrical O KN. The patients with congenital esotropia showed poor nasal to tempor al OKN regardless of the degree of stereopsis or timing of surgery. Co nclusions: Our results indicate that good binocularity, as measured by stereopsis, is not sufficient for the development of symmetric OKN in patients with congenital esotropia.