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).
It is unknown what exactly causes eye blisters, but they are most common in the elderly and generally occur in those who spend a lot of time outdoors without proper sun protection for the eyes. The smallest type of eye blister, the pterygium, is generally painless and may come in small clumps of tiny clear lesions. They may occur almost anywhere on the eye, including the cornea, and can sometimes cause temporary vision changes.