TENASCIN AND CYTOKINES IN TEAR FLUID AFTER PHOTOREFRACTIVE KERATECTOMY

BACKGROUND: Basic knowledge of the substances involved In wound healin g after photorefractive keratectomy (PRK) is essential for development of pharmacological intervention. We present preoperative and postoper ative analysis of tear fluid extracellular matrix proteins and cytokin es after PRK. METHODS: Tear fluid samples from 70 patients (72 eyes) w ho had PRK (38 women and 32 men, mean age 31.5 yr) were studied, Sampl es from 18 patients (18 eyes) were analyzed in two different studies. RESULTS: Mean preoperative tear fluid flow in the collection capillary (volume divided by tear collection time) varied.from 4.5 to 22.5 mu l /min in five series of patients. It increased significantly during the first two postoperative days (range of means, 55.5 to 88.8 mu l/min, p < 0.01), and decreased to the preoperative level by day 7 (range of means, 9.7 to 18.2 mu l/min).The tenascin and cytokine release rates i ncreased significantly during the first two days after PRK and returne d to the preoperative level by day 7, Mean +/- standard error for tena scin: day 0 (5.2 +/- 1.9 ng/min); day 2 (22.7 +/- 6.1 ng/min; p=0.02). Mean +/- standard error for HGF: day 0 (3.2 +/- 0.7 pg/min); day 1 (2 2.8 +/- 4.2 pg/min; p=0.0003). Mean +/- standard error for TGF-beta 1: day 0 (63.3 +/- 19.6 pg/min); days 1-2 (826.2 +/- 253.7 pg/min; p=0.0 01). Mean +/- standard error for VEGF: day 0 (166.0 +/- 29.6 pg/min); days 1-2 (824.4 +/- 165.1 pg/min; p=0,0007). Mean +/- standard error f or PDGF-BB: day 0 (0.42 +/- 0.19 pg/min); day 2 (27.6 +/- 5.8 pg/min; p=0.0000). Mean +/- standard error for TNF-alpha: day 0 (9.5 +/- 2.8 p g/min); day 2 (28.6 +/- 5.9 pg/min; p=0.003). Excluding PDGF-BB, all s ubstances studied were present in normal human tear fluid. PDGF-BB was present in only 17% of the preoperative samples. CONCLUSION: Corneal wounding induces an increased release of several growth modulating cyt okines which may be involved in healing processes.