To the Editor.
—Morrison and Swan1 observed a split in Descemet's membrane in 15 of 23 corneas examined after penetrating keratoplasty. Although Descemet's membrane itself can split into two layers, the anterior banded and posterior nonbanded layers, it is more likely that corneas with long-standing pathology, such as interstitial keratitis and aphakic corneal edema, show this split between Descemet's membrane and the posterior collagenous layer of cornea.The term posterior collagenous layer of the cornea designates any collagen-containing tissue, either cellular or acellular, deposited posterior to the normal Descemet's membrane.2 This tissue has also been designated as a thickened, duplicated, or multilaminar Descemet's membrane and is commonly called a retrocorneal membrane. The more precise term, posterior collagenous layer of the cornea, designates this tissue as a distinct senescent or pathologic entity, rather than confusing it with the normal Descemet's membrane or with basement membranes in general. It
Waring GO. Penetrating Keratoplasty. Arch Ophthalmol. 1984;102(8):1121. doi:10.1001/archopht.1984.01040030903005