A condition in which light rays entering the eye are not focused on the retina, causing blurred vision. 

Progressive optic nerve damage that leads to progressive loss of vision usually occurs because of increased pressure in the eye.

A clouding (opacity) of the lens of the eye that causes a progressive, painless loss of vision

A condition that causes progressive damage to the macula, the central and most vital area of the retina, resulting in gradual loss of central vision.