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.
The classic treatment for a moderately lazy eye has long been an eyepatch, covering the stronger eye with a patch, forcing the weaker eye to do enough work to catch up. However, eyedrops can work as well as an eyepatch in correcting moderate lazy eye and preventing the development of amblyopia. Atropine eyedrops are instilled daily in the stronger (dominant) eye. The atropine works by blurring rather than blocking vision in the stronger eye.
Severe strabismus may require surgery. The surgery is designed to increase or decrease the tension of the small muscles outside the eye. (These muscles are called the extraocular eye muscles. The six extraocular eye muscles move the eye in all directions.) When strabismus surgery is needed, the sooner it is done, the better the chance of the child achieving normal binocular vision.
Adults sometimes also need strabismus surgery. This can be done in a standard manner, as in children. Or adjustable suture surgery may be done because scarring from old eye surgery, inflammation from eye muscle disease, or neurological eye weakness makes it difficult to gauge how much tension to take up or let out to straighten the eyes. With adjustable suture surgery, it is possible to adjust the tension of the muscles after the surgery.