Damping of intraocular pressure fluctuations

Background: There is increasing evidence that relatively rapid spikes in intraocular pressure may contribute to axonal damage in glaucoma. The present study seeks to quantify the ability of a compressible damping element (a simple air bubble) to reduce intraocular pressure fluctuations induced by a known change in intraocular fluid volume. Methods: A mathematical model describing the damping of intraocular pressure increases for a given infusion volume was developed and compared with experimental data obtained from isolated pig eyes. A damping element (100 mu L to 2 mL of air) was added to the system, and the effect on the induced intraocular pressure change for a given infusion volume was assessed. Results: The introduction of the damping element reduced the intraocular pressure change in a volume-dependent manner consistent with the mathematical modelling. The maximum bubble size tested (2 mL) dampened the intraocular pressure change by an average of 63.5 +/- 8.7% at a baseline pressure close to 20 mmHg. Close agreement was seen between the mathematical model and the experimental data. Conclusion: Mathematical modelling and experiments in isolated pig eyes demonstrated that the addition of a damping element in the form of a compressible air bubble is capable of significantly reducing induced intraocular pressure spikes.