Evaluating Eye Tracking During Dichoptic Video Viewing With Varied Fellow Eye Contrasts in Amblyopia

This study uses eye tracking to investigate how varying fellow eye (FE) contrast during dichoptic video viewing influences eye movement patterns, and their associations with interocular suppression, visual acuity, and stereoacuity deficit in amblyopia.

Eye movements of 27 amblyopic and 8 healthy control participants were recorded during dichoptic viewing of stationary dots and videos with FE contrasts (100%, 50%, 25%, and 10%). Analysis included durations the amblyopic and FE spent in different stimulus regions, fixation switches, and eye deviation, and correlating these with suppression, visual acuity, and stereoacuity.

Participants with pronounced suppression, visual acuity, and stereoacuity deficits demonstrated reduced amblyopic eye fixation in the amblyopic eye (AE) region at 100% FE contrast. Lowering FE contrast increased amblyopic eye duration in stimuli presented within the AE region, notably in anisometropic and treated strabismic participants, and strabismic participants exhibiting fixation switches during viewing of dichoptic stationary dots. Even at lower FE contrasts, participants with greater stereoacuity and visual acuity deficits continued to exhibit diminished AE fixation in the AE region. Increased eye deviation was seen in strabismic participants with lowering of FE contrasts.

Dichoptic contrast modulation holds promise for reducing suppression with responses varying by amblyopia type and visual function deficits. Larger strabismic angles may hinder binocular benefits of dichoptic treatments. Fixation switches may serve as an indicator of favorable outcomes. Eye tracking is crucial for understanding these dynamics, providing essential insights into visual attention dynamics of the FE and AE, and may serve as a valuable tool in optimization of amblyopia treatments.