• Ocular surface failure
• stem cell
• cornea
• stem cell deficiency
• stem cell transplantation, ocular surface

The ocular surface disease that results from corneal epithelial stem cell deficiency poses a difficult management problem. From the patient's perspective the eye from has little or no vision, is often cosmetically unsatisfactory, and may be uncomfortable or painful. The clinical consequences are recurrent or persistent epithelial defects that place the cornea at risk of thinning, vascularisation or infection. However, in a proportion of cases the eye may be otherwise healthy with good visual potential. Because the problem is often bilateral, an effective treatment offers a significant gain in quality of life.1–3

Corneal epithelial stem cells are located in the basal epithelial layer of the limbus. Epithelial stem cell deficiency can result from chemical or thermal injury, or can develop after acquired inflammation, such as in Stevens–Johnson syndrome or mucous membrane pemphigoid; although the clinical picture of aniridic keratopathy is similar the aetiology is uncertain. Trauma or inflammation can kill the limbal stem cells and destroy the environment that they rely on for growth and replication (the stem cell niche). It is not known whether limbal stem cells survive anatomically but remain non-functional in an altered environment. Irrespective of the cause, the final common pathway to disease is a characteristic picture of conjunctivalisation of the surface of the cornea in which the epithelial layer contains goblet cells and the epithelial cells themselves express an altered cytokeratin profile that is characteristic of conjunctiva.4–6 Associated scarring of the conjunctiva and lids, with lid and lash malposition, and dry eye disease are common. These problems must be corrected before surface reconstruction is attempted, otherwise any transplant of tissue or cells is unlikely to survive.

In 1989 Kenyon and Tseng reported that a corneal epithelial phenotype could be restored by direct transfer of …