Amblyopia, also known as “lazy eye”, is the leading cause of vision loss in children, resulting in reduced visual acuity and stereo acuity (poor depth perception). Amblyopia occurs when the visual system receive two different images from the eyes, mainly due to eye deviation (strabismus) or different refractive errors between the eyes (anisometropia). Because the brain cannot process different images simultaneously, it suppresses the visual information coming from the affected eye.

The worldwide prevalence of amblyopia is up to 3%. Although treatable, delayed or inaccurate diagnosis and treatment often result in partial vision loss.

Unless it is successfully treated in early childhood amblyopia usually persists into adulthood, and is the most common cause of permanent one-eye vision impairment among children and young and middle-aged adults. An estimated 2%–3% of the population suffer from amblyopia.