The part of the eye that light waves pass through first is the cornea, a transparent layer of the eyeball. The cornea bends light waves coming into the eye before they reach the lens, according to the American Optometric Association.
The cornea actually contains several layers but does not contain blood vessels. The epithelium is the outermost layer of the cornea that prevents foreign substances from entering the eye, says the National Eye Institute. Bowman's layer lies beneath the epithelium and contains collagen. The stroma lies beneath Bowman's layer and makes up the bulk of the cornea. Descemet's membrane exists beneath the stroma and protects the eye against injury. The endothelium is the innermost layer; it maintains fluid balance within the stroma.