20/20 just means the eyes can see letters on the eye chart, but to be able to read and learn effectively, both eyes have to work together as a team! Click the link below to watch a story about Kyle, a young third grader who was seeing double, which made it hard for him to focus on the page. He was labeled at school with learning/behaviour issues, but it turned out to be a vision problem for which he is now being successfully treated!
It is possible to train the eyes to work together, and the training can also have a positive impact on reading and schoolwork.

http://newyork.cbslocal.com/2015/05/26/add-misdiagnosis-eye-problems/