The concept of “sight testing” was developed to describe a refraction (a procedure that measures prescription of the eye) when it is administered independently from a comprehensive eye health examination and used to generate a record from which to dispense glasses or contact lenses. While refraction is an essential component of a comprehensive eye examination, it is but one of several factors considered by optometrists in the determination and maintenance of eye and vision health. Visual acuity can be addressed by corrective lenses, some other form of vision rehabilitation or further medical evaluation.