Quantitative Assessment of Fixational Disparity Using a Binocular Eye-Tracking Technique in Children with Strabismus

Fixational eye movements are important for holding the central visual field on a target for a certain period. In this study, we aimed to quantitatively assess fixational dispari-ties using binocular eye-tracking in strabismus children (before and after surgical alignment) and normal children. Fixational disparity of 117 children (4 – 18 years; 57 with strabismus and 60 age-similar normal controls) were recorded under binocular viewing with corrected refractive errors. Disparities in gaze positions relative to the target location were recorded from both eyes. Main outcome measures included fixa-tion disparities along horizontal and vertical axes in the fixation test. Children with strabismus exhibited significant (P<0.001) fixational disparities than normal children in both horizontal and vertical directions. Additionally, children with esotropia versus exotropia had poorer fixational function. Fixational disparities were significantly de-creased in the horizontal direction after strabismus surgery. A significant negative correlation was observed between binocular best-corrected visual acuity and fixation disparities in children with strabismus. Children with strabismus had significant fixa-tional disparities that were observably diminished in the horizontal direction after surgical alignment. Binocular assessment of fixational disparities can provide a more comprehensive evaluation of visual function in strabismus