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.