Abstract
Purpose:
During intraocular surgery, intraocular pressure (IOP) fluctuations can increase the risk of perioperative complications and minimizing the IOP fluctuation may lead to better surgical outcome. We performed an experimental study as laboratory investigation to measure the fluctuation in infusion pressure and IOP in vitrectomy with flow-based IOP control system and to evaluate the efficacy of the "IOP control limit" module and valved cannula on attenuating infusion pressure fluctuation.
Methods:
This preclinical study was conducted using three porcine eyes. We measured the infusion pressure and IOP simultaneously in real time during vitreous cutting and aspiration and after extraction of instrument in which the exhaust cannula was held open. We also evaluated the efficacy of valved cannulas and built-in "IOP control limit" module on attenuating the fluctuation of infusion pressure. Following parameters were altered in each surgical maneuvers: 1) the flow-based IOP control setting turned on or off; 2) IOP control limit setting turned on or off; and 3) set pressure of the device of 20, 30, 40, 50, or 60 mmHg. Each individual experiments were repeated 10 times, and the mean values were calculated. The main outcome measure was the fluctuation of the infusion pressure during various vitrectomy maneuvers.
Results:
In vitrectomy with IOP control setting turned on, infusion pressure increased to maintain the IOP at the set pressure level. At the set pressure level of 30 and 60 mmHg, the mean infusion pressure was 43.7 and 78.7 mmHg in the vitreous cutting mode, 67.4 and 101.2 mmHg in the aspiration mode and 72.8 and 115.8 mmHg when the exhaust cannula was held open in the 23-gauge system, respectively. Use of valved cannula attenuated the fluctuation of both infusion pressure and IOP efficiently. When the IOP control limit setting turned on, compensatory infusion pressure increase was markedly limited. Infusion pressure was similar to set pressure level at the IOP control limit level 2. Similar results were obtained with the 25-gauge system.
Conclusions:
Great infusion pressure increase was observed during vitrectomy with flow-based IOP control system. The use of valved canulas and "IOP control limit" module attenuated the compensatory infusion pressure increase in this system.