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Yoshimi Sugiura, Fumiki Okamoto, Yoshifumi Okamoto, Takahiro Hiraoka, Tetsuro Oshika; Changes in Intraoperative Intraocular Pressure During 20-gauge Pars Plana Vitrectomy Using the Vented Gas Forced Infusion System. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6115.
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To measure changes in intraoperative intraocular pressure (IOP) during 20-gauge pars plana vitrectomy using the Vented Gas Forced Infusion (VGFI) system, and to investigate IOP fluctuations during various vitrectomy manipulations.
In porcine eyes, core vitrectomy was performed using 20-gauge system, and a 22-gauge cannula was inserted into the vitreous cavity. The cannula was connected to a pressure transducer via conditioning modules to a chart recorder for continuous monitoring of intraoperative IOP. By changing the VGFI setting from 30 to 60 mg, the time for IOP to rise from 30 to 60 mmHg was measured. The VGFI setting was changed from 30 to 10 mmHg, and similar measurement was conducted. The IOP fluctuations were recorded during various surgical manipulations, including vitreous cutting, aspiration, and scleral compression.
It took 0.8 sec for IOP to rise from 30 to 60 mmHg when the VGFI setting was changed, and 3.9 sec was needed for the IOP to drop from 30 to 10 mmHg after the VGFI setting change. By vitreous cutting with aspiration pressure of 200 mmHg, IOP decreased from 30 to 13.7 mmHg in 0.9 sec, and vitreous cutting with 300 mmHg aspiration decreased IOP to 8.3 mmHg in 1.9 sec. By aspiration with 200 mmHg pressure, IOP decreased from 30 to 0 mmHg in 3.0 sec. Scleral compression without aspiration rapidly increased IOP to 90.9 mmHg and release of compression decreased IOP to 3.9 mmHg in 0.2 sec. Gentle scleral compression and release with mild aspiration fluctuated IOP between 22.3 and 33.1 mmHg.
IOP fluctuations were assessed during 20-gauge vitrectomy with the VGFI system. There was a considerable time lag between the timing of VGFI setting change and actual IOP change, especially when the pressure setting was lowered. Vitrectomy manipulations induced significant and varied amount of fluctuations in IOP.
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