A SHORT SIGHTED (MYOPIA)
Also known as nearsightedness, is a refractive error in which you see better close up than from a distance. Myopia is caused because an eye is too long to focus light on the retina or a cornea which is too steeply curved. In these cases distant light focuses in front of the retina rather than sharply on the retina.
B FAR SIGHTED (HYPEROPIA)
Also known as farsightedness, is a refractive error in which you see better from a distance than close up. Hyperopia is caused because an eye is too short to focus light on the retina. Light strikes the retina before it can come to a sharp focus.
C BLURRY VISION (ASTIGMATISM)
Astigmatism is blurry vision produced by mis-shaped corneas, which are too steep in one plane and too flat in another. Astigmatic corneas focus light in two different places in the eye, making both near and distance vision a problem.
Is the difficulty with reading that develops as people enter their 40s and older. This is a natural part of the ageing process and occurs because the lens within the eye is less flexible as we age.