Dasha Vanichkina¹, Nicole Dranitsaris¹, Martin Arguin^2,3, Alexandre Reynaud^1,4; ¹McGill University, ²Université de Montréal, ³Centre de recherche, Institut Universitaire de Gériatrie de Montréal, ⁴Research Institute of the McGill University Health Centre

Amblyopia, or “lazy eye”, is a condition where incoming visual information from one eye is processed poorly in the brain and binocular integration is disrupted. It is known that reading is altered in amblyopia; individuals affected by this condition tend to have a slower reading speed and present different eye movement patterns compared to controls. We believe that differences in visual oscillatory mechanisms of amblyopic participants may account for this dissimilarity. Thus, we used the novel method of random temporal sampling to evaluate this theory. In the present study, we aimed to investigate whether there are differences in the temporal features of the reading efficiency of controls and amblyopic subjects. Six amblyopic and six control participants were tested monocularly and binocularly. Participants were asked to read three to six letter words presented for 400 ms and sort them into one of four categories. During exposure, the visibility of targets varied randomly through time by manipulating the signal (target word) to noise (white noise field) ratio. Classification images, which reflected processing efficiency, were calculated based on response accuracy, which was maintained at 50%. As anticipated, controls read more efficiently overall and were most efficient in the binocular condition. Amblyopic participants processed most efficiently with their non-amblyopic eye and struggled the most in the binocular condition. Lastly, controls showed an overall better level of binocular summation than amblyopic participants, meanwhile amblyopic subjects seemed unable to integrate binocular visual information to aid them in word identification. Overall, our results demonstrated that the temporal features of processing efficiency of controls and amblyopic subjects differ in meaningful ways during reading. These results have implications for the development of treatments for amblyopia that specifically target high-level processes.

Acknowledgements: This research was funded by the Vision Sciences Research Network mobility grant to DV; an NSERC discovery grant RGPIN-2024-06447 and a startup fund from the RI-MUHC to AR; and operating NSERC and FRQST grants to MA.