Pilot Clinical Trial to Assess the Safety of Limbus-derived Corneal Stem Cells in Prevention of Corneal Haze After Photo Therapeutic/Refractive Keratectomy (PTK/ PRK) and Collagen Cross Linking (CXL)

In this pilot clinical trial, patients undergoing Photo Therapeutic/Refractive Keratectomy (PTK/ PRK) and Collagen Cross Linking (CXL), will be given human Limbus-derived Corneal Stem cells to assess the safety of these cells. Cells will be cultivated in a cGMP laboratory using standardized culture technique; from the limbal rims of cadaveric corneoscleral donor tissues that are therapeutically accepted and serologically tested. Briefly the limbal tissue will be cut up into small pieces and digested overnight using an enzyme (Collagenase L). The cells obtained from the digest will be cultured on a petri-dish using 2% serum and growth factors. A mixture of limbal epithelial cells and limbal stromal cells obtained from these cultures will be used in surgical procedures in a ratio of 2:1, after all the sterility checks. Mixed suspension of the limbal epithelial and the stromal cells at a concentration of 50000 cells/uL diluted in the thrombin component of fibrin sealant (TISEEL, Baxter) will be applied. The primary outcome measure is safety of this treatment and the secondary outcome measure is their efficacy that will be assessed at 1 month time points by (1) Clinical photography using a standard method where multiple blinded observers will grade the clinically apparent change in haze and (2) Objective quantification of the amount of light scattering using densitometry analysis function in Oculus Pentacam (OCULUS Optikgeräte GmbH).