Myopia (short sight); Things in the distance are blurred but things get clearer the closer they get.
Hypermetropia (long sight); Things are clearer in the distance than up close up.
Astigmatism; This is a distortion of focusing making things blurred for near and far.
Cataracts; The lens inside the eye can become opaque. This often happens as the eye ages and can cause the vision to become very blurred. Cataracts can be corrected much more easily than they used to be. The cataract is replaced with a clear plastic lens within the eye giving almost normal vision back again.
Glaucoma; A disease of the eye where the pressure inside the eye causes damage and if undetected could lead to blindness. This is usually corrected using drops to relieve the pressure in the eye so no further damage is done. Unfortunately there are virtually no symptoms to this condition and it is usually only detected on visiting the optician.