correction of various eye vision disorders by lens. hyperopia, myopia, astigmatism.

anatomical anatomy astigmatism blurred care concave convex cornea corrected correction cross cylindrical defect disease disorder disorders eye eyeball eyesight farsighted farsightedness focus health human hyperopia illustration lens light long longsighted longsightedness minus myopia nearsighted nearsightedness normal optometry poor problem ray refractive retina short shortsighted shortsightedness sighted sightedness structure various vector vision