Purposes: To determine the stability of subjects’ visual acuity, refraction, corneal topography, pachymetry, anterior chamberdepth, and intraocular pressure following overnight orthokeratology when subjected to vertical acceleration at sixtimes the force of gravity (+6 Gz) in a simulated ejection system on the ground. Methods: The subjects were 10 healthymale fl ight surgeons, aged 25–26 years (mean 25.3), who had undergone overnight orthokeratology for two weeks beforecontrolled rapid-sequence ejection at +6 Gz. Their visual acuity, refraction, and corneal parameters, including cornealcurvature, corneal thickness, anterior chamber depth, and intraocular pressure, were recorded before, immediately after,and 20 min after the +6 Gz ejection. We compared the study group fi ndings with those of a control group of 20 subjectswho had not undergone orthokeratology but were exposed to the same ejection procedure. Results: The measurementsof visual acuity, refraction, and Orbscan topographic parameters, including the anterior and posterior corneal curvatures,central corneal thickness, and intraocular pressure, made before, immediately after, and 20 min after ejection did not differsignifi cantly between the pre- and post ejection values on paired t tests. The only signifi cant difference in the orthokeratologygroup was in the anterior chamber depth, which was 2.978 mm before ejection and 3.01mm 20 min after ejection (p< 0.05). Conclusion: The visual acuity, refraction, and corneal topographic changes in patients after orthokeratology arestable under rapid vertical ejection at six times the force of gravity. An increase in anterior chamber depth was the onlysignifi cant change after ejection in the orthokeratology group.