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).
Eye twitching is causes blepharospasm. There are many causes of eye twitching. The common ones are alcohol, caffeine, fatigue, lack of sleep, physical exertion, smoking, stress, and irritation to the eye or eyelid.