As the use of digital resources is increasing in classrooms, the issue of their accessibility for students with visual impairment included in regular classrooms needs to be addressed. The goal of our study is to assess the accessibility of digital textbooks for visually impaired students as compared to sighted students. Relying on results observed in the field of web or e-learning accessibility (Coyne & Nielsen 2001; Evans, 2008; Giraud & al., 2017) we hypothesized that when interacting with a digital textbook to perform learning or navigation tasks, visually impaired students will show higher mental load, longer times to reach the goal, lower performances than their sighted peers, because of a higher amount of working memory resources used for activities that are not relevant for learning (i.e. extraneous cognitive load).