Types of defective vision

The transparent cornea constitutes the anterior border of the eye. Behind it lies the iris with the pupil. Directly behind that sits the lens. At the far right in the illustration is the location of the retina which occupies the rear interior section of the eye. With a normal-sighted eye (emmetropia) the beams of light are refracted by cornea and lens in a way that those are precisely focused on the retina.