In this cross section of a cornea in a person with Fuchs' dystrophy, the green rectangles represent endothelial cells. The magenta dots are outgrowths of Descemet's membrane known as guttae. Guttae are bumps on the back surface of the cornea that grow larger as the disease progresses. During Descemet's stripping automated endothelial keratoplasty (DSAEK), Descemet's membrane and the endothelium are stripped away. Only part of the donor cornea is transplanted. This tissue includes a very thin layer of the corneal stroma, and the Descemet's membrane and endothelium. The tissue is held in place by an air bubble until it adheres to the back of the patient's cornea and begins to function, removing excess water from the swollen cornea.