Congenitally Impaired Disparity Vergence in Children With Infantile Esotropia

Abstract

PurposeWe examined whether congenital impairment of disparity vergence in infantile esotropia (ET) exists in children with short duration ET (≤3 months) compared with long-duration ET and healthy controls. A short duration of misalignment would allow for a substantial amount of balanced binocular input during the critical period of binocular disparity development.MethodsA total of 19 children aged 5 to 12 years and treated for infantile ET with a short (≤3 months; n = 10) or long (≥5 months; n = 9) duration of constant misalignment before alignment were enrolled. A total of 22 healthy control children were enrolled as a comparison group. Eye movements during disparity vergence and accommodative vergence were recorded using an EyeLink 1000 binocular eye tracker. Mean response gain was compared between and within groups to determine the effect of duration of misalignment and viewing condition.ResultsCompared with controls, children with short (P = 0.002) and long (P < 0.001) duration infantile ET had reduced response gains for disparity vergence, but not for accommodative vergence (P = 0.19).ConclusionsRegardless of duration of misalignment, children with infantile ET had reduced disparity vergence, consistent with a congenital impairment of disparity vergence in infantile ET. Although early correction of misalignment increases the likelihood that some level of binocular disparity sensitivity will be present, normal levels may never be achieved.

Unilateral Amblyopia Affects Two Eyes: Fellow Eye Deficits in Amblyopia

“…However, this evidence has thus far been indirectly inferred. Moreover, fellow eye deficits may reflect mechanisms not considered hereevidence from infantile strabismus, for example, indicates that congenital impairment of binocular function is possible, 278,279 which would also account for deficits in the fellow eye. These possibilities highlight the importance of planning studies to directly investigate the role of fellow eye deficits in the amblyopic visual system, and how they change over time in relationship to the sensitivity of the amblyopic eye.…”

Neural mechanisms of oculomotor abnormalities in the infantile strabismus syndrome

“…It is clear that NHP models of infantile strabismus have many striking similarities to human infantile-onset strabismus. On the other hand, recently some authors have argued that human infantile strabismus syndrome may be associated with a primary, congenital neural deficit of the disparity-driven vergence system (Kelly et al 2016). In primate models, abnormalities of this system presumably do not develop until after birth, when researchers intervene to prevent binocular vision.…”

Fixation instability during binocular viewing in anisometropic and strabismic children

“…Binocularly discordant visual experience in infancy or early childhood from anisometropia (unequal refractive error), strabismus (misalignment of the visual axis), or a combination of both can hinder visual maturation during this critical period of rapid brain development. Even when treated with optical correction and/or surgical alignment, these pediatric eye conditions are associated with a constellation of visual deficits that include amblyopia (i.e., decreased visual acuity in one eye -'lazy eye') (Birch, 2013), binocular dysfunction (i.e., impaired stereoacuity, interocular suppression) (Birch, 2003(Birch, , 2013Birch and Stager, 2006;Birch et al, 2016;Li et al, 2011), and ocular motor impairment (i.e., abnormal saccade initiation and execution) (Niechwiej-Szwedo et al, 2012;Niechwiej-Szwedo et al, 2010), reduced vergence (Kelly et al, 2016), and fixation instability (Birch et al, 2013;González et al, 2012;Subramanian et al, 2013).…”