Keratocytes: no more the quiet cells.

BACKGROUND: In the past, the keratocytes of the adult cornea have been characterized as quiescent cells populating the stroma. Recent research and the introduction of laser refractive procedures have forced us to reassess this notion.
METHODS: By reviewing recent, pertinent papers, an attempt was made to give an overview of the new information the scientific community is learning about keratocytes. This overview assesses the heightened interest in the keratocytes, while maintaining a clinical perspective. Where applicable, this information was tied in with our own laboratory observations.
RESULTS: It is becoming increasingly clear that keratocytes may play a vital role in regulating the stromal constituents, while also providing structural stability in maintaining the interlamellar organization and, thus, promote corneal transparency. Keratocytes form a communicating network of cells linked in a anterior-posterior fashion, as well as laterally. This ability to communicate appears instrumental in triggering and orchestrating the corneal response in wound healing. External corneal injury, such as epithelial debridement and excimer laser exposure, can cause profound anterior keratocyte loss. These cells are replaced by aggressive stromal cells, which may play an important role in the formation of scar tissue and corneal haze.
CONCLUSION: Keratocytes play an important role in both the healthy and the injured cornea. It appears that the improved outcomes of laser refractive procedures will--to a large extent--depend on our ability to maintain keratocyte health, while also controlling the negative effects of cells replacing injured or dead keratocytes.