[In vitro evaluation of pressure fluctuations with differing height of the infusion bottle in phacoemulsification]

To investigate the influence of the height of the infusion bottle and vacuum pressure on the development of an occlusion break surge in an in vitro model of the anterior chamber of the eye.

We employed a rigid chamber device to simulate the anterior chamber of the human eye and performed phacoemulsification with a synthetic nucleus. We evaluated amplitude of pressure fluctuations in the chamber. An experimental occlusion break surge was produced at vacuum pressures of 200, 300, and 400 mmHg. For each vacuum setting, the height of the infusion bottle was preset from 60 to 90 cm at intervals of 5 cm. We performed 6 measurements for each condition.

Increase in surge deflection amplitude was proportional to the increase in vacuum pressure (p < 0.0001). At all vacuum pressures, there was no significant relation between surge deflection amplitude and bottle height. Amplitude of pressure fluctuations in the chamber did not fall below the irrigating pressure if the bottles were kept 70 cm at a vacuum pressure of 200 mmHg, and 85 cm at a vacuum pressure of 300 mmHg. At a vacuum pressure of 400 mmHg, surge deflection amplitude always exceeded irrigating pressure, even if the bottle height of 90 cm was chosen.

Increases in vacuum pressure led to increase in amplitude of occlusion break surge. Elevation of the infusion bottle did not decrease the amplitude of occlusion break surge, but increased the pressure in the chamber at the beginning of the surge and prevented the pressure in the chamber from falling below the irrigating pressure.