Amblyopia (commonly known as “lazy eye”) is a common developmental visual disorder, caused by eye misalignment, unequal refractive error between two eyes, or visual deprivation, with lifelong consequences on learning and academic achievements that we do not fully understand. It affects 4.7% of Canadian children, and 22-41% of children do not respond to conventional treatment. The proposed study aims to improve our understanding and treatment of amblyopia by looking at aspects of vision that are known to be disrupted by amblyopia but are not currently part of the clinical definition. Behavioural and neuroimaging measures will be used with children and adolescents. The goal is to identify the neurophysiological mechanisms underlying treatment outcomes, which in future will allow clinicians to recommend specific treatment strategies depending on the deficits with which a child presents.