Fig. 20. Keratoconus. Top left. Clinical photograph in lateral projection demonstrates extreme anterior protrusion of the markedly ectatic cornea. Top middle. Acute hydrops, due to a break in Descemets membrane is accompanied by extreme stromal and epithelial edema. Top right. Following resolution of acute hydrops, slit lamp biomicroscopy delineates the extent of Descemet's membrane rupture (between arrowheads). Bottom left. Phase-contrast microscopy of a cornea with healed hydrops shows the retracted and detached ledge of Descemet's membrane (DM) which, along with the posterior stromal surface, has been completely resurfaced by endothelial cells (*). S, posterior stroma (paraphenylenediamine × 250). Bottom right. Transmission electron micrograph of area circled in previous figure shows portion of a recovering endothelial cell (En) lining the stroma anterior to Descemet's membrane ledge. The layer of basement membrane material (*) represents the initial attempt at reformation of Descemet's membrane. AC, anterior chamber (× 27,000). (Top left. Grayson M: Diseases of the Cornea, p 256. St. Louis, CV Mosby, 1979)