Occult Duane syndrome: co-contraction revealed following strabismus surgery

Three patients presented in infancy with large angle esotropia and limited abduction. Narrowing of the lid fissures with globe retraction on horizontal gaze became apparent only after recession of the medial recti. Abduction remained limited. Two of the three exhibited dissociated vertical deviations, and seemed to have both congenital esotropia and Duane syndrome. The third had an unusual pattern of apparent co-contraction in which the eye attempting abduction actually adducted. Although rare, Duane syndrome may occur in children with large angle esotropia, and its presence may not be revealed until after strabismus surgery.