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).
Causes of eye twitching. Eye twitching, or blepharospasm, is an uncontrollable blinking or spasm of the upper eyelid. Most people develop a minor eyelid twitch at some point in their lives. The causes include: Fatigue; Stress; Caffeine; This minor form of twitch is painless and harmless. It usually goes away on its own. But it can be quite annoying.