Additional issues associated with reading problems are convergence insufficiency, esotropia and exophoria. Convergence insufficiency is caused when the two eyes cannot focus inward on the reading, therefore making it difficult for the child or adult to read and process what is being read. Convergence insufficiency can be corrected using eye exercises to retrain the eyes to focus inwardly together. Esotropia is when both eyes are open, one turns inward. Exophoria is when one eye turns outward when both eyes are open. Both conditions are commonly referred to as lazy eye because the eye that is turning inward or outward is not performing the task that the other eye is, therefore it is considered lazy.