The Relationship Between Interocular Lag and Contrast Sensitivity in Amblyopia

Abstract

Purpose: Previous studies have reported a processing time difference between the two eyes in unilateral amblyopia. In the current study, we measured the interocular lag (IOLag) and contrast sensitivity across different spatial frequencies (SFs) to investigate (1) whether the interocular lag varies as a function of SF and (2) whether the temporal binocular imbalance depends on contrast sensitivity. Methods: Twenty adult participants with amblyopia and 20 healthy controls participated in this experiment. We measured the IOLag by using a continuous tracking task. One white-noise condition and 5 different SFs: 0.5, 1, 2, 4, and 8 c/deg were tested. The contrast sensitivity function (CSF) was assessed using the quick contrast sensitivity function (qCSF) procedure. Results: In healthy controls, we observed IOLags close to 0 at all SFs. Amblyopic individuals exhibited a significant IOLag across all SFs compared with controls (F1,38 = 13.8, P = 0.001), with a mean value of 35.2 ms. In addition, we found that the mean IOLag in amblyopia was positively correlated with the area under the log CSF ratio (AULCSF; rho = 0.611, P = 0.004) and that the absolute IOLag was correlated with interocular visual acuity (VA) difference (rho = 0.614, P = 0.004). Conclusions: We demonstrated that the IOLag depends on SF in amblyopia. In addition, we found that this temporal imbalance of amblyopia was linked with their spatial imbalance. This temporal asynchrony in amblyopia should not be ignored in amblyopic visual deficits and vision rebuilding.

The authors' abstract, as published at the source. Investigative Ophthalmology & Visual Science, 2026 · DOI ↗