arcus senilis

This is a white haze or ring on the cornea that occurs with age. The cornea is the clear window that makes up the front of the eye. This living tissue has no blood vessels running through it because it needs to be perfectly clear. To get its nutrition, the cornea depends upon the tear film on the outside, the aqueous fluid on the inside, and blood vessels on the sclera (the white of the eye) that run right up to the edge of cornea before stopping. Lipid and cholesterol fats travel in our blood stream, and over a lifetime, can leach out of the blood vessels and deposit themselves in a ring in the cornea.  This white ring is called arcus senilis and is a normal aging change that has no effect on vision.  When I see this in only one eye (or in a young person) I start looking into other problems such as circulation or cholesterol abnormalities.