Yan-Ru Chen¹ (), Shu-Qi Jiang¹, Xiang-Yun Liu², Jun-Yun Zhang¹; ¹Peking University, ²The Affiliated Tengzhou Hospital of Xuzhou Medical University

Purpose: The brain perceives global contours by integrating discrete but collinear stimuli. While previous studies have primarily explored contour integration deficits in amblyopia within the spatial domain, this study investigates how amblyopia affects contour integration over time, and examines the relationships between temporal contour integration deficits and visual functions. Methods: Nineteen amblyopic children (10.9 ± 2.7 years; 17 anisometropic, 2 anisometropic/strabismic mixed) and twenty-six visually normal children (10.5 ± 1.8 years) participated in this study. We measured the accuracy of detecting tilted contour paths formed by collinear Gabor elements under slit-viewing conditions for amblyopic eyes (AEs) and fellow eyes (FEs) separately at two spatial frequencies (1.5 cpd and 3 cpd). The slit width, orientation jitter of contour elements, and stimulus moving speed were varied in separate runs. Visual acuities for both eyes and Randot stereoacuity were assessed before the testing. Results: (1) The AEs exhibited deficits in temporal contour processing compared to FEs at average_interelement_distances (AIED) of 0.8, 1, 2, and 4. Slit width thresholds for AEs were significantly higher than for FEs, and were correlated with AE visual acuity at 1.5 cpd. (2) Increased orientation jitter of contour elements and changing stimulus speed reduced contour detection accuracy, eliminating the differences between AEs and FEs. (3) There were significant temporal contour deficits in AEs compared to control eyes, while no differences between FEs and control eyes. (4) Temporal contour integration deficits in amblyopia were not correlated stereoacuity, or spatial contour integration deficits. Conclusions: Amblyopic children demonstrate deficits in temporal contour integration in AEs, which appear to be independent of spatial contour integration deficits. Children with more severe visual acuity impairments in AEs tend to have more pronounced temporal contour integration deficits. These findings suggest that amblyopia is associated with temporal deficits in visual integration, in addition to known spatial deficits.

Acknowledgements: Supported by the Natural Science Foundation of China grants 31970978 and 32371079 (JYZ; Beijing, China).