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).
Medical Definition of Lazy eye. Lazy eye: An eye that diverges in gaze. A lazy eye is formally called strabismus. A lazy eye (strabismus) can be due to esotropia (cross-eyed) or to exotropia (wall-eyed). The danger of the condition is that the brain comes in time to rely more on one eye than the other and that part of the brain circuitry connected to the less-favored eye fails to develop properly, leading to amblyopia (blindness) in that eye.