defects in this world?????

i thing associates with the eyes are myopia (shortsightedness)when the eyeball elongates and the image is unable to reach the retina amd the person cannot see distant obeject; (b) hypermetropia (long-sight) when the lens becomes less convex so the image is formed behind the retina.persons suffering from it cannot see an object; astigmatism when the curvature of the cornea becomes uneven and no image is correctly formed.