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 specific period of time. In this study, we aimed to quantitatively assess fixational disparities using binocular eye tracking in children with strabismus (before and after surgical alignment) and healthy children. Fixational disparities in 117 children (4-18 years; 57 with strabismus and 60 age-similar healthy controls) were recorded under binocular viewing with corrected refractive errors. Disparities in gaze positions relative to the target location were recorded for both eyes. The main outcome measures included fixational disparities along horizontal and vertical axes in the fixation test. Children with strabismus exhibited significant (p < 0.001) fixational disparities compared to healthy children in both horizontal and vertical directions. Additionally, children with esotropia had poorer fixational function compared to those with exotropia. The occurrence of fixational disparities significantly decreased in the horizontal direction following strabismus surgery. A significant negative correlation was observed between binocular best-corrected visual acuity and fixational disparities in children with strabismus. Children with strabismus had significant fixational 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 individuals with strabismus.