Abstract: PURPOSE: This study aims to evaluate the effects of monocular flicker stimulation on binocular imbalance in patients with amblyopia.
METHODS: Seven amblyopic patients (28.3 ± 3.3 years, four females) and seven normally sighted participants (27.3 ± 4.1 years, five females) were included. The balance point (BP), where participants’ two eyes are equally effective, was measured using a binocular orientation combination task under baseline conditions and with monocular flicker at five temporal frequencies (TFs, 4, 7, 10, 15, and 20 Hz). |logBP| were calculated and normalized to the baseline condition to analyze the influence of monocular flicker on binocular imbalance. Negative normalized |logBP| values indicate improved balance.
RESULTS: Adding monocular flicker to the amblyopes’ fellow eye (FE) resulted in normalized |logBP| values below zero, indicating improved balance. Conversely, when flicker was added to the amblyopic eye (AE) or to the nondominant eye (nonDE) or dominant eye (DE) of normal participants, normalized |logBP| values were above zero, indicating disrupted balance. The mixed repeated-measures ANOVA revealed no significant difference in normalized |logBP| values between flicker applied to AE in amblyopes and nonDE in normal (P = 0.481). However, when flicker was applied to the FE in amblyopes, normalized |logBP| values were significantly lower than when applied to the DE in normal (P < 0.001).
CONCLUSIONS: While flickering the amblyopic eye disrupted balance, flickering the fellow eye improved binocular imbalance in amblyopes. These findings have implications for therapeutic interventions targeting binocular balance in amblyopia.

Key words: monocular flicker, temporal frequency, interocular interaction