Eye Tracking Abnormalities in School-Aged Children With Strabismus and With and Without Amblyopia

Purpose: To detect eye tracking abnormalities in children with strabismus in the absence or presence of amblyopia. Methods: A total of 100 patients aged 7 to 17 years were enrolled prospectively for 2 years from the pediatric ophthalmology clinic of the American University of Beirut Medical Center: 50 children with strabismus (including 24 with amblyopia) and 50 age- and gender-matched controls. Eye tracking with different paradigms was performed. Results: Mean age was 10.66 +/- 2.90 years in the strabismus group and 10.02 +/- 2.75 years in the control group. Demographic characteristics were similar with respect to vision, gender, and refraction. Four paradigms were tested using the eye tracker: (1) distance/near paradigm: patients with strabismus showed a lower fixation count and longer fixation at both distances and a tendency for decreased latency and percentage of fixation in distant elements; (2) reading paradigm: the strabismus group had a higher fixation count and duration, especially those without amblyopia; (3) location identification paradigm: strabismus group without amblyopia fixated less and with shorter duration on the most flagrant element; and (4) video paradigm: no differences in eye movements were noted. Conclusions: Significant eye movement deficits were demonstrated in patients with strabismus compared to controls while reading text and identifying prominent elements in a crowded photograph. This was significant in the non-amblyopic subgroup.