Limbal transplantation for ocular surface reconstruction

Proliferation of the corneal epithelium originates in undifferentiated, lon g-lived stem cells that are located in the basal limbal epithelium. Stem ce lls are important for corneal epithelial regeneration and wound healing. De pletion of stem cells due to accidents as well as malfunctions of stem cell s due to inborn or inflammatory diseases result in timbal stem cell deficie ncy. Limbal deficiency is characterized by conjunctivalization of the corne a with vascularization and opacification. Partial limbal deficiency can be treated by removing ingrown conjunctival epithelium thus allowing normal li mbal epithelium to repopulate the cornea. Unilateral limbus-derived stem ce ll disease requires either timbal autograft transplantation from the health y partner eye or kerato-timbal allograft transplantation. Several modificat ions of the latter technique have been performed including large kerato-tim bal lamellar grafts and central penetrating kerato-timbal allografts. All h omologous procedures render a very high risk of immunological reactions tha t require long term systemic immunosuppression. The use of amniotic membran e, better pharmacological drugs for immunosuppression and improvements in t he HLA-matching of limbal allografts as well as ex vivo expansion of cornea l stem cells should allow for better reconstruction of the ocular surface i n limbal deficiency.