Historically, penetrating keratoplasty, or full thickness corneal transplantation, was the treatment of choice for irreversible endothelial failure. More recently, new corneal transplant techniques have been developed to enable more selective replacement of the diseased corneal endothelium. This approach, termed endokeratoplasty, is most appropriate for disease processes that exclusively or predominantly involve the corneal endothelium. Penetrating keratoplasty is preferred when the disease process involves irreversible damage not just to the corneal endothelium, but to other layers of the cornea as well. Compared to full-thickness keratoplasty, endokeratoplasty techniques are associated with shorter recovery times, improved visual results, and greater resistance to wound rupture. Although instrumentation and surgical techniques for endokeratoplasty are still in evolution, one commonly performed form of endokeratoplasty at present is Descemet's Stripping (Automated) Endothelial Keratoplasty (DSEK DSAEK). In this form of endokeratoplasty, the diseased host endothelium and associated Descemet's membrane are removed from the central cornea, and in their place a specially harvested layer of healthy donor tissue is grafted. This layer consists of posterior stroma, Descemet's membrane, and endothelium that has been dissected from cadaveric donor corneal tissue, typically using a mechanized (or "automated") instrument.