The outer, transparent, dome-like structure that covers the iris, pupil, and anterior chamber. The cornea provides approximately two-thirds of the optical power of the eye. Light passes into the eye through the cornea allowing vision. Light also passes out of the eye allowing the iris and pupil of the eye to be seen. The cornea can be considered to have five layers:

1. Corneal epithelium

2. Bowman's layer

3. Corneal stroma

4. Descemet's layer

5. Corneal endothelium.