When my son was in kindergarten, he was diagnosed with a "lazy eye." I do not know if that is still the appropriate term to use, but the result was that he had to wear a patch over one eye (the stronger one) to force the other eye to work harder and to strengthen. In the book The Pirate of Kindergarten, by George Ella Lyon, the main character, Ginny, receives a similar diagnosis when she does not pass a routine vision screening at school. Ginny has difficulty seeing. She runs into things in the classroom, and some of her classmates laugh at her. Ginny loves reading but when she reads she has trouble seeing the letters, and she has to get very close to the page. The imagery of the letters hopping "around like popcorn" and the number 2 looking more like a swan help bring the reader into Ginny's world.