Concise review: identifying limbal stem cells: classical concepts and new challenges.

The presence of a clear cornea is required for vision, and corneal epithelial cells play a key role. There is a long held view, supported by decades of study, that corneal epithelial stem cells reside at the limbus to regulate homeostatic cell turnover and wound healing. However, the identification of specific markers that allow the isolation and characterization of limbal stem cells remains elusive. Here, we review the classical concepts of limbal stem cell identity and highlight the current state of the field.