These are vision disorders that cannot be corrected with glasses, lenses or any surgery and are not caused by an eye disease.

The most common cause is strabismus. Different refractive power between the two eyes, high hyperopia and astigmatism are the other main causes of amblyopia. Reasons such as keeping one eye closed for a period of time during infancy and early childhood, or congenital cataracts that prevent or reduce the light entering the eye are also among the causes of lazy eye.