Which of the following is NOT a corneal layer?

• A. Epithelium
• B. Stroma
• C. Bruch's membrane
• D. Descemet's membrane

Answer: (C)

The cornea has a well-defined set of layers forming its clear, protective front surface: the outer epithelial layer, a middle thickness called the stroma, and two inner basement membranes—Descemet's membrane and the corneal endothelium (with Bowman's layer sometimes described between epithelium and stroma). Bruch's membrane, however, is not part of the cornea. It is a thin layer located in the posterior eye, between the retinal pigment epithelium and the choroid, within the retina’s supporting structures. Because it belongs to the retina-choroid complex and sits at the back of the eye, it is not a corneal layer. This makes it the correct choice for identifying something that is not part of the cornea.