Cornea

The cornea is the transparent front surface of the eye through which light enters. Shaped like a gently domed lens, it provides most of the eye’s refractive power, meaning most of the bending that light undergoes inside the eye.

That refractive role is why the cornea is where most laser vision correction takes place. Changing its curvature changes where light comes into focus inside the eye.

The cornea has no blood vessels and draws nutrients from the tear film and from the fluid in the anterior chamber. Its clarity depends on not holding too much water, which is the job of an inner cell layer called the endothelium.