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).
Strabismus (crossed eyes) is the most common cause of amblyopia. There is often a family history of this condition. The term lazy eye refers to amblyopia, which often occurs along with strabismus. However, amblyopia can occur without strabismus. Also, people can have strabismus without amblyopia.