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).
7 Causes for Eye Twitching. Another reason for twitching eyes may be a lack of sleep or fatigue resulting from it. Fatigue resulting from physical exertion or inadequate sleep can both cause the eye to twitch. Just as fatigue has the potential to affect other muscles in the body, it can do the same to muscles of the eyelid as well.