An assessment of intraocular pressure change in healthy subjects during air flight

To investigate the effect of air flight on intraocular pressure (IOP).

Baseline IOP of 25 healthy volunteers was measured at a ground level of 1760 feet above sea level (ASL) using Tono-Pen XL. Measurements were repeated after reaching an altitude of 19,000 feet and then on the second hour during a routine flight. Cabin pressure was kept around 8000 feet. IOP measurement was repeated after landing (3.5 hr after taking off). Change in the IOP was evaluated.

Mean +/- SD IOP was 14.2 +/- 2.7 mmHg at ground level and was 14.0 +/- 2.2 mmHg after gaining maximum altitude (p = 0.78). Mean IOP dropped to 12.3 +/- 2.5 mmHg on the second hour of flight and 12.0 +/- 1.7 mmHg after landing. Decrease in IOP on the second hour (13.4%, p = 0.005) and after landing (15.7%, p = 0.001) were significant.

IOP significantly decreased on the second hour measurements during a routine flight, and this change was sustained after landing.