The cornea is a clear tissue that covers the front of each eye. Light entering the eye first passes through the cornea, then the pupil (the dark spot at the center of the coloured iris), and then the lens.

A corneal transplant is the process of removing all (Penetrating keratoplasty), or part of (DSEK, DSAEK, DALK), a cloudy or abnormally shaped cornea and replacing it with a healthy donor’s cornea.