Assertion: cornea's layer | /r/HasProperty | extreme tough
Facets:
value: to penetrate protecting the eye
type: PURPOSE
Source sentences:
text: The cornea is made up of five distinct layers: the epithelium, the outermost, protective layer of the cornea; the Bowman membrane, this second layer is extreme tough and difficult to penetrate further protecting the eye; the stroma, the thickest layer of the cornea, consisting of water, collagen fibers and other connective tissue components that give the cornea its strength, elasticity and clarity; Descemet membrane, a thin, strong inner layer that also acts as a protective layer; and the endothelium, the innermost layer consisting of specialized cells that pump excess water out of the cornea.