The very surface layer of the cornea (epithelium) is being continuously replaced by new epithelium, while the old epithelium is being shed off, a process similar to surface of the skin. This cycle is crucial for maintaining healthy ocular surface, corneal clarity and good vision. Each healthy cornea has stem cells located in the periphery of the cornea (called limbus). Corneal limbal stem cells are special cells that have ability to continuously produce new epithelial cells and maintain healthy corneal surface. In a spectrum of ocular disorders such as chemical burn, aniridia, and autoimmune diseases (e.g. Stevens-Johnson syndrome, toxic epidermal necrolysis, ocular cicatricial pemphigoid) stem cells may become permanently damaged to a degree that prevents their function, which leads to a compromised ocular surface, irritation, redness and decreased vision due to loss of corneal clarity. To treat this state of limbal stem cell deficiency, limbal stem cell grafts can be harvested from a donor and transplanted onto the ocular surface of a patient. The donor graft can be harvested from the patient's fellow eye, from a relative, from another living donor with healthy ocular surface, or from a cadaver.