低压缺氧对LASIK术后视功能的影响

Effects of low pressure hypoxia on visual function after laser in situ keratomileusis

目的 观察LASIK术后人群在低压缺氧环境中视功能变化情况,了解准分子激光角膜屈光手术眼在飞行特殊环境的适应性.方法 自身前后对照研究.20名（40眼）健康志愿者,平均年龄为（23.8±1.2）岁,准分子激光近视矫正术后1年.低压舱上升前测量眼压、近立体视、色觉、屈光度、对比敏感度（双眼明视、暗视眩光下空间频率3、6、12、18c/d的对比敏感度值）,低压舱以30 m/s速度上升至5000 m高度,在此高度停留10 min后再次测量,此过程无供氧,测量后低压舱以10～15 m/s速度下降至地面.对相应数据采用配对t检验进行分析.结果 低压舱实验前后眼压未见明显变化[（右眼（13.0±1.7）mmHgvs.（13.0±2.1）mmHg,t=-0.56,P＞0.05;左眼（13.0±2.0 mmHg vs.（13.0±2.0） mmHg,t=-0.81,P＞0.05）];近立体视[（21.5±2.4）弧秒vs.（27.6±8.3）弧秒,t=-3.39,P＜0.05）及色觉（9.60±2.73vs.27.20±8.57,=-2.81,P＜0.05）]下降;等效球镜度[（右眼（-0.90±0.61）Dvs.（-1.08±0.75）D,t=1.71,P＞0.05,左眼（-1.21±0.61）Dvs.（-1.06±0.54）D,t=-1.33,P＞0.05）差异无统计学意义;对比敏感度（18 c/d暗视眩光环境对比敏感度降低P＜0.05,其他情况均未见降低）.结论 低压缺氧环境对准分子激光术后远期人群的眼压、屈光度、对比敏感度（除高频暗视眩光）均无影响;近立体视、色觉及高频暗视眩光条件的对比敏感度下降.

Objective To test the effects of altitude hypoxia on visual function after laser in situ keratomileusis （LASIK） and to evaluate flight adaptability after laser refractive surgery.Methods This was a self-control designed study.Forth eyes of 20 healthy males with a mean age of 23.8±1.2 years volunteered for this prospective study.All patients had bilateral LASIK surgery 1 year prior to the study.Interocular pressure,near stereopsis,color vision,refractive error,contrast sensitivity （CS） （photopic,scotopic＋glare environments; 3,6,12,18 c/d spatial frequencies） were measured before exposure to the hypobaric chamber.The atmosphere in the chamber ascended to an equivalent of a 5 000 m altitude at the rate of 30 m/s.Subjects were measured again after remaining there for 10 minutes without an oxygen supply.The chamber then returned to ground level at the rate of 10-15 m/s.Data were analyzed using a paired t test.Results There were no significant differences in intraocular pressure or spherical equivalent refractive error for either eye before and after the hypobaric experiment：right eyes：13.0±1.7 mmHg vs.13.0±2.1 mmHg,t=-0.56,P＞0.05,-0.90±0.61 D vs.-1.08±0.75 D,t=1.71,P＞0.05; left eyes：13.0±2.0 mmHg vs.13.0±2.0 mmHg,t=-0.81,P＞0.05;-1.21±0.61 D vs.-1.06±0.54 D,t=-1.33,P＞0.05）.Near stereopsis （21.5±2.4 vs.27.6±8.3,t=-3.39,P＜0.05） and color vision （9.60±2.73 vs.27.20±8.57,t=-2.81,P＜0.05） were depressed.Contrast sensitivity was depressed only at 18 cycles/degree in the scotopic＋glare environment.Conclusion Based on this study,we conclude that hypoxia has little effect on interocular pressure,refractive error or CS except at 18 c/d in the scotopic＋glare environment after LASIK surgery.Near stereopsis,color vision and CS at 18 c/d in the scotopic＋glare environment were reduced.