EPIDERMAL GROWTH-FACTOR IN THE TEAR FLUID - RESPONSIBLE FOR POSTOPERATIVE REFRACTION AND HAZE AFTER PRK

Background: Corneal wound healing is of critical importance for the po stoperative outcome of excimer laser PRK. Wound healing is a complex b iological process that is well characterised at the microscopic level, but its regulation is poorly understood at the molecular level. Among Various cytokines, epidermal growth factor (EGF) plays an important r ole in superficial wound healing. The synthesis of EGF varies individu ally; therefore, by determining the EGF concentration in the tear flui d, patients with increased wound healing activity might be traced. Met hods: In this study we measured the EGF concentration pre- and postope ratively in the tear fluid of 50 eyes using a ELISA test. The preopera tive refraction was between -2.00 and -10.00 dioptres. The maximum fol low-up was 6 months. Results: Preoperatively, in all eyes the EGF conc entration in the tear fluid was between 0.2 and 1.7 ng/ml. In contrast , 1 week postoperatively, these values increased (0.21-22.50 ng/ml); 4 weeks postoperatively, the EGF concentration was in all eyes back to preoperative levels. In eyes with high EGF tear fluid concentration 1 week after surgery, refraction at 6 months was outside the intended co rrection of +/- 1.0 D. We could not find any correlation between EGF c oncentration and ''corneal haze'' Conclusions: EGF may play an importa nt role in postoperative wound healing after excimer laser PRK. Invest igations concerning a pharmaceutical control of EGF should be undertak en.