Active_comparator: Ultra-thin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK)

Ultra-thin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) refers to the use of a corneal endothelial/Descemet graft with a thin layer of stroma (\<110um) attached.~The cornea is made up of 5 layers, all of which work to provide a clear image on the retina. The innermost layer of cells, the endothelium, is responsible for pumping fluid out of the cornea and keeping it transparent: a normal endothelium is essential to keeping the cornea clear. The endothelium lies on a membrane called the Descemet membrane. The thickest layer of the cornea is called the stroma and this provides rigidity and strength to the cornea. When the corneal endothelium fails, it cannot regrow and the best treatment is to replace the cells with healthy donor cells. This is called a corneal endothelial transplantation or endothelial keratoplasty.~In the DSAEK technique, a piece of the donor's endothelium is transplanted with a supporting layer of donor stroma.

Active_comparator: Descemet membrane endothelial keratoplasty (DMEK)

Descemet membrane endothelial keratoplasty refers to the use of a corneal endothelial/Descemet graft with no layer of associated stroma (15-20um thick).~The cornea is made up of 5 layers, all of which work to provide a clear image on the retina. The innermost layer of cells, the endothelium, is responsible for pumping fluid out of the cornea and keeping it transparent: a normal endothelium is essential to keeping the cornea clear. The endothelium lies on a membrane called the Descemet membrane. The thickest layer of the cornea is called the stroma and this provides rigidity and strength to the cornea. When the corneal endothelium fails, it cannot regrow and the best treatment is to replace the cells with healthy donor cells. This is called a corneal endothelial transplantation or endothelial keratoplasty.~In the DMEK technique only a piece of donor endothelium layer is together with its supporting membrane (the Descemet membrane), is transplanted.