Functional Burden of Strabismus: Decreased Binocular Summation (BiS) and Binocular Inhibition

Binocular summation (BiS), defined as the superiority of visual function for binocular over monocular viewing, decreases with age and large interocular differences in visual acuity (VA). In extreme cases, patients may have binocular inhibition whereby their binocular vision is worse than that of their better eye alone. BiS has not been well-studied as a functional measure of binocularity in strabismus. Additionally, there are multiple subjective complaints in strabismus patients that are not easily explained by current knowledge of their binocular function. We hypothesized that strabismus patients may have diminished BiS and perhaps binocular inhibition.