Since 1986, we believe that the cornea is epithelial stem cells free and all the epithelial stem cells are localized in the limbus. As a consequence, if the limbus and the corneal epithelial stem cell niche are destroyed the cornea loses its normal differentiation and transdifferentiate in conjunctiva. We call these diseases: limbal stem cell deficiency. According to the model of corneal epithelial stem cells we also classified diseases of the ocular surface as diseases related to a lake of epithelial stem cells.Discussion:
Recent data have shown that there are epithelial stem cells in the central cornea of 5 different mammals. In human, central corneal epithelial cells can divide 50 times in vitro, and central corneal epithelial cells can survive for a long period after total destruction of the limbus. Furthermore, epithelial cells after epithelial ingrowths after LASIK or FEMTOLASIK exhibit corneal epithelial stem cells characteristics. In conclusion, all these data challenge the model we use to explain the renewing of the corneal epithelium and in consequence how we call and classify the diseases of the ocular surface.