Will Descemet's stripping with automated endothelial keratoplasty (DSAEK) lower the rates of allograft rejection in corneal transplants for endothelial failure?

BACKGROUND: Allograft corneal rejection occurs in a substantial number of full thickness transplants in spite of the relative immune privilege enjoyed by the cornea. Compared to other layers of the cornea, endothelial rejection has most disastrous consequences on graft survival. In the last few years, a new technique, Descemet's stripping with automated endothelial keratoplasty (DSAEK) is being used of selective transplantation of the endothelium. It involves stripping diseased endothelium (and Descemet's) and replacing it by a small lamella fashioned from a cadaveric donor cornea, which consists of endothelium, Descemet's membrane and a part of posterior stoma. HYPOTHESIS: We hypothesize that DSAEK might substantially reduce the incidence of allograft immune rejection in corneal transplant done for cases with endothelial failure. EVALUATION OF THE HYPOTHESIS: In published reports of consisting of more than 300 surgeries and three years experience with DSAEK, no case of graft rejection has been reported. In our opinion, this advantage of DSAEK compared to conventional full thickness keratoplasty could be due to four factors: (a) The transplanted tissue is placed in the anterior chamber and has no exposure to the surface, where the antigen presenting cells (APC) and antibodies are present. (b) Significant reduction in the number of sutures connecting the host and donor tissue may lead to lesser suture related rejection episodes. (c) Absence of direct contact between the host stroma vessels and the transplanted tissue disrupts the immune affecter and effecter arcs. (d) Reduced immunogenicity of the donated tissue due to absence of epithelium. CONSEQUENCES OF THE HYPOTHESIS: If this hypothesis stands true in subsequent studies, it could lead to substantial reduction in the socioeconomic resources involved in management of graft rejection. Even if this hypotheses fails the test of well controlled studies, this would broaden the current understanding of the ocular immunology and the immune privilege with which the anterior chamber of the eye is normally associated with.