At age 12, Andrew Bastawrous was told by his teachers that he was slow and inattentive. But the results of an eye exam explained why: he had very poor vision. Globally, as many as 2.5 billion people who need glasses don't have them -- and are unable to reach their full potential as a result. Now an eye surgeon, Bastawrous shares his brief but spectacular take on eradicating avoidable blindness.