Stem cells of the corneal epithelium are located at the limbus and areultimately responsible for renewal and regeneration of the corneal epitheliumunder normal circumstances and during wound healing. Diseases causing eithera complete loss of limbal epithelial stem cells or severe destruction of the limbalstroma result in the pathologic state of total limbal stem cell deficiency.A new technique termed ex vivo expansion of limbal epithelial stem cellshas been developed to treat patients with limbal stem cell deficiency.