BackgroundDescemet membrane endothelial keratoplasty (DMEK) has become the standard surgical treatment for Fuchs' endothelial corneal dystrophy (FECD) in Germany. In addition to classical FECD, there are endothelial disorders amenable to DMEK associated with complex changes in the anterior segment of the eye, such as anterior synechia of the iris, larger iris defects, after glaucoma surgery, after vitrectomy and after trauma.ObjectiveThis article provides an overview of the possibilities to treat patients with complex anterior segment situations in the presence of corneal endothelial decompensation with DMEK.Material and methodsDescription of problems and current surgical techniques when performing DMEK in complex situations.ResultsReconstruction of the iris or the iris/lens diaphragm often needs to be performed either simultaneously or in aprevious operation to treat patients with complex anterior segment alterations with DMEK. Both very shallow and very deep anterior chambers pose amajor problem. A DMEK graft from older donors (above 70years) is prone to less rolling and should be preferred in patients with adeep anterior chamber (e.g. after vitrectomy). The graft size should also be adapted to the available space, e.g. asmaller graft diameter should be selected for eyes with anterior synechia.ConclusionThere are only afew evaluations of DMEK under complex conditions; however, it appears that the rate of secondary graft failure, endothelial cell loss and the rebubbling rate are increased in this very heterogeneous group of diseases. Further studies are needed to identify risk factors for anegative progression after DMEK in complex eyes