Effects of transient high intraocular pressure during LASIK on NO and NOS activity in retinal tissues

GUAN Wenying; ZHAO Haixia; WANG Zhaoge; GE Ruichun; WANG Ruifang

doi:10.3969/j.issn.1002-266X.2016.04.004

Abstract：Objective To observe the effects of transient high intraocular pressure ( IOP) caused by negative pressure suction at different time of duration during laser-assisted in situ keratomileusis ( LASIK) on the changes of NO and NOS in retinal tissues and to investigate the safe time of negative pressure suction during LASIK. Methods Sixteen-eight New Zealand white rabbits were randomly divided into the normal control group ( n=4 ) , the experimental control group ( n=4), 20 s suction group (n=20), 45 s suction group (n=20) and 3 min suction group (n=20), whose time of negative pressure suction was respectively 20 s, 45 s and 3 min. LASIK surgical procedure was simulated, and the experimental control group only received laser ablation and the normal control group without any treatment. The animals in the suction groups were executed immediately (0 d), after 7 d, 10 d, 14 d and 28 d. The rabbits in the experimental control group were executed after laser ablation. Meanwhile, the rabbits in the normal control group were executed. The NO content and NOS activity in retinal tissue of each group were detected by 752 spectrophotometer. Results NO content and NOS activi-ty:no significant difference was found between the normal control group and the experimental control group ( all P >0. 05), no significant difference was found at every postoperative time between the 20 s suction group, 45 s suction group and normal control group (all P>0. 05), no statistically significant difference was found between the 3 min suction group and the normal control group immediately after operation (all P>0. 05). Seven days and 10 day after operation, the NO content and NOS activity in the 3 min suction group were higher than those of the normal control group (all P<0. 05). No significant difference in the NO content and NOS activity was found between the 3 min suction group and the normal control group 14 days and 28 days after operation (all P>0. 05). The NO content and NOS activity reached a peak 7 d after oper-ation, and they were positively correlated with each other (r=0. 982, P<0. 05). Conclusions Conventional suction of 20 s and 45 s in LASIK does not cause the change of NO content and NOS activity in the retinal tissues. When the suction time extends to 3 min, the NO content and NOS activity, but this change is reversible increase, after 28-day restoration, it can return to normal.