Purple halo around brown eyes?

Arcus senilus: Really depends on your age. Most commonly a benign condition in those over 40-45. Occasionally some metabolic and triglyceride or choletetol disorders will cause a ring at the periphery of the cornea.

Lipid (Fat) Deposits: Although this ring may look purple in people with brown eyes it is actually opaque white/grey. It is caused by lipid (fat) deposits around the periphery of the cornea. It is called arcus senilis. It is a benign finding and occurs commonly but in certain patients can rarely indicate elevated cholesterol and if asymmetric can indicate narrow blood vessels.