The Effect of an Air Bubble in the Anterior Chamber on the Change in Intraocular Pressure (IOP)

Purpose: To compare rate of change in IOP with and without air bubbles in the anterior chamber (AC).

Methods: Enucleated porcine eyes were infused with Balanced Salt Solution (BSS) at 10μl/min. In one experiment, 5 eyes each were injected with 0.15 or 0.30ml bubbles without prior removal of aqueous humour while 5 controls were not injected. In another experiment, 9 eyes were injected with 0.30ml bubbles with prior removal of 0.30ml aqueous humour while 8 controls were not injected. The rate of change in IOP from 5mmHg to 20mmHg was compared. Statistical analysis involved the unpaired t-test and one–way ANOVA. P<.05 was considered statistically significant.

Results: In the first experiment, after initial spikes IOP settled to +3.5+/-3.4mmHg and +4.7+/-5.1mmHg from the original baseline with 0.15ml and 0.30ml respectively (P=.13). The rate of change was 0.25+/-0.09mmHg/min for controls, 0.31+/-0.12mmHg/min for 0.15ml and 0.46+/-0.10mmHg/min for 0.30ml. The difference between the control and 0.30ml groups was significant (P=.02). In the second experiment, IOP after injection was 5.3+/-1.6mmHg compared to 5.9+/-0.7mmHg in the control group (P=.30). The rate of change in IOP was 0.28+/-0.09mmHg/min with bubbles and 0.30+/-0.08mmHg/min without (P=.68).

Conclusion: An air bubble in the AC does not affect the rate of increase in IOP.