Anterior Chamber Air Bubble Dynamics With Decreases In Atmospheric Pressure

To evaluate the effect of decreasing barometric pressure on intracameral bubble size and intraocular pressure in eyes with varying air fillings of the anterior chamber.

Medical University of Vienna

36 human donor eyes received either 30%, 50% or 90% anterior chamber air fillings. The eyes were subjected to decreases in atmospheric down to 750hPa, equal to 2400m in altitude and were repeatedly imaged using anterior segment OCT, while IOP was measured continuously.

Eyes with 30% air filling initially showed moderate increases in IOP yet rising to an average of 30.83mmHg at 850hPa (mimicking 1400m altitude) and 42.08mmHg at 750hPa. Eyes with larger air bubbles showed more acute rises in IOP with increases to an average of 47.25mmHg in eyes with 50% air filling at 850hPa and 63.33mmHg at 750hPa. In eyes with 90% air in the anterior chamber, IOP readings of an average of 113.42mmHg were observed already at 850hPa, at which point further pressure reduction was not performed.

While severe increases in IOP were observed with decreased atmospheric pressure in eyes with large air bubbles in the anterior chamber, small and moderately sized bubbles appear to allow for travel with modest changes in altitude.