Chronic pain: Pain (an unpleasant sense of discomfort) that persists or progresses over a long period of time. In contrast to acute pain that arises suddenly in response to a specific injury and is usually treatable, chronic pain persists over time and is often resistant to medical treatments.
Common causes of the condition include: 1  Muscle imbalance (strabismus). The most common cause of lazy eye is an imbalance in the muscles that position the eyes. 2  Difference in sharpness of vision between the eyes (refractive anisometropia).
Amblyopia, or lazy eye, is the most common cause of visual impairment in children. It happens when an eye fails to work properly with the brain. The eye may look normal, but the brain favors the other eye. In some cases, it can affect both eyes. Causes include Read more on MedlinePlus.gov.