EGF and cholesteryl ester measurement: Besides, platelet-rich plasma (PRP) contains platelet, platelet derived growth factor (PDGF), transforming growth factor beta (TGF-β), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF) and other cytokines, in view of its regulatory actions on inflammation and local immune, PRP would be an effective alternative approach for patient with persistent CE.