Cataracts:

Cataracts are a clouding of the eye’s lens that causes blurriness and loss of vision. The word cataract literally means waterfall and when a cataract is severe it’s like trying to see through a waterfall. Cataracts occur when the protein that makes up the eye’s lens becomes clumped. Scientists believe that cataracts may be brought on by smoking and diabetes as well as the impact of ultraviolet light and general wear and tear on the protein of the lens over the years. Fortunately, cataracts are highly treatable. Cataract surgery, in which the clouded lens is removed and replaced with a clear plastic one, is both a relatively simple procedure and very successful in restoring sight.

Typical reading solutions are desktop magnifiers.

Also See:
Age Related Macular Degeneration
Glaucoma
Diabetic Retinopathy
Retinitis Pigmentosa