Release of TGF-beta 1 and VEGF in tears following photorefractive keratectomy

Purpose. To study the presence and release of tear fluid transforming growth factor-beta 1 (TGF-beta 1) and vasoendothelial growth factor (VEGF) of 19 patients undergoing excimer laser photorefractive keratectomy. Methods. Tear fluid samples were collected with scaled microcapillary tubes preoperatively (Day 0) and on the first or second (Day 1-2) and seventh (Day 7) postoperative days. Since postoperative tear fluid flow was significantly higher, we calculated the release of both growth factors by multiplying the con concentration by the tear fluid flow in the capillary. Results. The median tear fluid flow in the capillary was 8.1 mu l/ min (range 0.7-20.8) on Day 0, 46.3 mu l/min (3.1-135.1) on Day 1-2, and 10.2 mu l/min (1.8-65) on Day 7. The median TGF-beta 1 concentration and release values were: Day 0: 4.5 ng/ mi (0-23) and 24 pg/min (0-257), Day 1-2: 9 ng/ml (0-32) and 446 pg/min (0-4602; p = 0.0014), and Day 7: 6.5 ng/ml (0-44) and 53 pg/min (0-470), respectively. The median VEGF concentrations and releases were: Day 0: 19 ng/ml (14-23) and 128 pg/min (11-458), Day 1-2: 15 ng/ml (11-20) and 695 pg/min (14-2567; p = 0.0007), and Day 7: 17.5 ng/ml (15-22) and 167 pg/min (27-1235), respectively. Conclusions. TGF-beta 1 and VEGF are components of normal tear fluid. The significantly increased release of both growth factors after excimer laser photorefractive keratectomy may influence the corneal wound healing process.