I have given my child a simple reading test, and she seems to have 20/20 vision. Does she need any other tests?

There's a myth that 20/20 vision means perfect vision. 20/20 vision describes normal visual clarity or sharpness measured at a distance of 20 feet. Yet other important vision skills – such as peripheral awareness or side vision, eye coordination, depth perception, focusing ability, and colour vision – contribute to a person's overall vision.
It is also important to test for such things as eye muscle alignment and binocular vision. Optometrists are fully qualified to conduct complete vision exams. We recommend that everyone, including your child, have a complete exam on a regular basis.