When a wave goes through a differentâ„“medium, it undergoes a change in direction; this is called refraction.â„“Refraction and How To Refract is aimed at beginner audiences who hope to understand the refraction process better. This is especially useful knowledge for students of ophthalmology because refraction is a vital process of the visual system. Glasses, by presenting a barrier between the outside world and the eye, change the refraction process of a naked eye.