cornea /kôr″nē·ə/ [L, corneus, horny] , the convex, transparent anterior part of the eye, comprising one sixth of the outermost tunic of the eye bulb. It allows light to pass through it to the lens. The cornea is a fibrous structure with five layers: the anterior corneal epithelium, continuous with that of the conjunctiva; the anterior limiting layer (Bowman’s membrane); the substantia propria; the posterior limiting layer (Descemet’s membrane); and the endothelium of the anterior chamber (keratoderma). It is dense, uniform in thickness, and nonvascular, and it projects like a dome beyond the sclera, which forms the other five sixths of the eye’s outermost tunic. The degree of corneal curvature varies among different individuals and in the same person at different ages; the curvature is more pronounced in youth than in advanced age. −corneal, adj.
