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).
In cases of crossed eyes, there is one eye that is off-focus from the object the person is trying to see. The brainâs natural tendency is to ignore the off-focus image, leaving the eye that produces it underused and weak. After time, this weakened eye may remain out of position, resulting in lazy eye.