Keratocytes

Keratocytes are specialized cells of the corneal stroma, the layer between the corneal epithelium and endothelium. They maintain the extracellular matrix (ECM) of the stroma and contribute to corneal transparency. In humans, keratocytes are derived from neural crest cells that populate the stroma during embryonic development.

In the healthy adult cornea, keratocytes are relatively quiescent, appearing as sparsely distributed, star-shaped cells with dendritic processes that lie between the collagen lamellae.

They synthesize collagen types I and V and major corneal proteoglycans such as lumican, keratocan, and decorin, and they regulate stromal hydration through glycosaminoglycans, helping to maintain precise collagen spacing and transparency.

In response to injury or surgery, keratocytes can become activated, differentiate into fibroblasts and myofibroblasts, migrate to the wound, and secrete ECM components to repair tissue. TGF-β signaling largely drives this activation. While it restores structure, excessive myofibroblast activity can disrupt collagen organization and cause haze or scarring; some cells may revert to a quiescent state.

Keratocytes are distinct from keratinocytes, which are epithelial cells of the skin and other epithelia. In clinical terms, keratocyte density and function can influence postoperative outcomes and corneal transparency after injury or surgery.