
A refraction test is usually given as part of a routine eye examination. It may also be called a vision test. This test tells your eye doctor exactly what prescription you need in your glasses or contact lenses. Normally, a value of 20/20 is considered to be optimum, or perfect vision. In other words, a refraction is an eye exam that measures a person’s prescription for eyeglasses. If you don’t have 20/20 vision, you have what is called a refractive error.