Strabismus: A condition in which the visual axes of the eyes are not parallel and the eyes appear to be looking in different directions. In divergent strabismus, or exotropia, the visual axes diverge. In convergent strabismus or esotropia, the visual axes converge. The danger with strabismus is that the brain may come to rely more on input from one eye than the other, and the part of the brain circuitry that is connected to the less-favored eye may fail to develop properly, leading to amblyopia (weakened vision) in that eye. The classic treatment for mild to moderate strabismus is to cover the stronger eye with a patch, forcing the weaker eye to do enough work to catch up. Atropine eyedrops can also be effective in correcting moderate lazy eye. Severe strabismus may require surgery. Also known as lazy eye.