Esotropia. An inward turning of the eye, esotropia is the most common type of strabismus. About one half of all cases of strabismus are due to a form of esotropia caused by excessive focusing, or accommodation. Accommodative esotropia frequently begins as an intermittent crossing and gradually becomes constant. The age of onset is usually about 2 years, but may be as late as 7. This child is farsighted and without glasses accommodates to see, resulting in crossed eyes. Glasses relieve this accommodative demand enabling the eyes to straighten.