vision defects 
Images do not form on the retina, thus resulting in blurry vision; such defects are corrected by eyeglasses, contact lenses or even surgery.
The image of an object is formed behind the retina due to a defect in the light rays’ convergence as they pass through the lens. This makes near objects hard to see.
Point where light rays converge to form an image; the brain interprets the retina’s upside-down image as right-side-up.
Corrects hyperopia by causing light rays emanating from an object to converge and project an image onto the focus of the retina.