What is the thickest corneal layer?

The stroma is indeed the thickest layer of the cornea, comprising about 90% of its total thickness. It is composed primarily of collagen fibers and is responsible for providing structural support as well as transparency to the cornea. The arrangement and interaction of the collagen fibers within the stroma are crucial for maintaining the cornea's shape and transparency, which are essential for proper vision.

In contrast, the epithelium, while it is the outermost layer, is much thinner and serves mainly as a protective barrier against environmental damage. Descemet's membrane and Bowman's layer are even thinner; Descemet's membrane serves as a basement membrane for the endothelium and plays a role in maintaining corneal shape, while Bowman's layer is a tough protective layer beneath the epithelium but does not contribute significantly to corneal thickness.