Cornea

The cornea is the clear outer layer of the eye through which you can see the Iris and Pupil. It has an index of refraction of 1.376, and a curved outer surface, contributing to the refractive state of the eye. The Cornea is about 80% of the eye's internal lens power. If you have LASIK or PRK surgery it thins the cornea to change your refractive state.