Lazy eye, or amblyopia, is the loss or lack of development of central vision in one eye that is unrelated to any eye health problem and is not correctable with lenses. It can occur when a person does not use both eyes together.

Lazy eye often occurs in people who have crossed eyes (misalignment) or a large difference in the degree of nearsightedness or farsightedness between the two eyes. It usually develops before age 6, and it does not affect the side (peripheral) vision.

Symptoms may include noticeably favouring one eye or a tendency to bump into objects on one side. Symptoms are not always obvious.

Treatment for lazy eye may include a combination of prescription lenses, prisms, vision therapy and eye patching. In vision therapy, patients learn how to use the two eyes together, which helps prevent the lazy eye from reoccurring.

Early diagnosis increases the chance for a complete recovery. This is one reason the American Optometric Association recommends that children have a comprehensive optometric examination by 6 months of age and again at age 3.

A lazy eye will not go away on its own. If not diagnosed until the preteen, teen or adult years, treatment takes longer and is often less effective.

Source: https://www.aoa.org/patients-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-conditions/amblyopia