The Relationship Between The Levels Of Nerve Growth Factor In Tears And Tear Film Stability After LASIK

Objective: To investigate the concentration of Nerve growth factor (NGF) in tears before Laser in situ keratomileusis (LASIK) and postoperatively, to identify the short term changes. And to study the mechanism of nerve growth factor in the dry eye after (LASIK).Methods: NGF levels in the tears of 34 Patients aged from 18 to 45 (male 16 eyes, female 18 eyes) were studied with a monoclonal antibody based ELISA before LASIK and 1 day, 2 days, 10 days, and 30days after LASIK. The patients aged from 18 to 45. Tear film stability was examined during the same visits. And then study the relationship between the levels of NGF in tears and tear film Stability in the eyes of pre and postoperative LASIK patients.Results:1. Compared the NGF mean values at Different Age and different sex pre and post-operation, there were no statistically significant differences (P＞0.05).2. The NGF mean value before LASIK was (20.47±4.93)μg/ml and mean values at 1 day, 2 days, 10 days, and 30 days after LASIK were(12.76±3.49)μg/ml, (11.01±459)μg/ml, (13.55±4.86)μg/ml, (19.37±5.16)μg/ml, respectively. The NGF levels in tears at the first three visits post-operation were significantly different from levels in the pre-operative group(P＜0.05). However, there were no statistically significant differences(P＞0.05)Compared among the three post-surgical groups. There was no significant difference between the pre-surgical level and the level at the 30days visit post-operation (P＞0.05).3. Tear film stability before LASIK was(12.09±1.67) seconds, and at 1 day, 2 days, 10 days and 30days after LASIK, it was(4.68±1.74)seconds, (4.85±1.89)seconds, (7.25±1.26)seconds, and (9.94±2.34)seconds, respectively. Tear film stability at the time of the four visits after surgery was significantly different from the preoperative level (P＜0.05).4.There was a positive correlation between tear film content and changes in tear film stability after LASIK(r=0.601, P＜0.01).Conclusion: The NGF mean value in the tears has no relativity with sex and it also has no relativity with age In certain range of age. The decrease of BUT is the cause of dry eye and the changes in tear film stability and the onset of dry eye after LASIK are related to the level of NGF.