What layers of cornea are involved in the LASIK flap cutting?

The corneal flap that is created in LASIK involves the outermost 3 of the 5 total layers of the cornea. Those are 1)epithelium, 2) Bowman's membrane, and 3) the stroma. The first of these is the protective layer (like epidermis in the skin). Bowman's layer is actually an interface between the epithelium and the stroma although it does vary in certain ways. The Stroma is the main and thickest part, the "wall" of the cornea.

A typical cornea is about 550 microns, i.e. 0.533 mm, thick at its center. A LASIK flap is usually about 100-150 microns thick.

_Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic