Purpose: To measure flow rate of balanced salt solution and IOP during simulated vitrectomy using two sets of high-speed dual-pneumatic probes.Methods: A closed-model eye system measured IOP and flow rate of a balanced salt solution through infusion cannula. The Constellation Vision System was tested with two sets of high-speed dual-pneumatic probes (UltraVit 23-gauge and enhanced 25þ-gauge 5000-cpm probes; UltraVit 23-gauge and enhanced 25þ-gauge 7500-cpm probes; n ¼ 6 each) under different vacuum levels and cut rates in three duty cycle modes.Results: In both probe sets, flow rates were dependent on cut rate with the biased open and biased closed duty cycles. Flow rates were highest with the biased open duty cycle, lower with the 50/50 duty cycle, and lowest with the biased closed duty cycle. IOP, as expected, was inversely associated with flow rate using both probe sets.

The shorter membrane attraction distance of the enhanced 27-gauge probe versus 23-gauge and enhanced 25-gauge probes may permit greater membrane dissection precision while providing improved access to small tissue planes. Equivalent fluid flow capabilities of the 27-gauge probe compared with the 23-gauge and 25-gauge probes may provide efficient aspiration. Surgeon selection of duty cycle modes may improve intraoperative fluid control and expand the cutter utility as a multifunctional tool.

PurposeWe aimed to investigate effects of instrument settings on porcine vitreous flow rates through dual pneumatic high-speed vitrectomy probes.MethodsThe CONSTELLATION® Vision System was tested with 250, 450, and 650 mmHg of vacuum using six ULTRAVIT® vitrectomy probes of each diameter (25+®, 25, 23, and 20 gauge) operated from 500 cuts per minute (cpm) up to 5,000 cpm. Duty cycle modes tested included biased open, 50/50, and biased closed. Flow rates were calculated by assessing the change in weight of porcine eyes during vitreous aspiration. Volumetric flow rate was measured with a computer-connected electronic scale.ResultsAt lower cut rates, the biased open mode produced higher flow than did the 50/50 mode, which produced higher flow than did the biased closed mode. In the biased closed and 50/50 modes, vitreous flow rates tended to increase with increasing cut rate. Vitreous flow rates in the biased open duty cycle mode remained relatively constant across cut rates.ConclusionVitreous flow rates through dual pneumatic vitrectomy probes could be manipulated by changing the duty cycle modes on the vitrectomy system. Differences in duty cycle behavior suggest that high-speed cut rates of 5,000 cpm may optimize vitreous aspiration.

PurposeTo evaluate the impact of high-speed cut rates (up to 7500 cuts per minute [cpm]) on vitreous flow through various gauge probes.MethodsAn open-sky vitrectomy technique was performed on porcine eyes using the CONSTELLATION Vision System with three different gauges of dual-pneumatic probes (27+-, 25+-, and 23-gauge UltraVit probes; n = 5 for each gauge). Flow rate was calculated by LabVIEW software that converted real-time mass measurements from an electronic scale into flow rate.ResultsAverage vitreous flow rate increased slightly with increased cut rate in all probes with 50/50 duty cycle; more dramatic flow rate increases were observed for all probes with biased closed duty cycle. Under both conditions, maximum flow rate was observed at 7500 cpm for all gauges. Under the biased open duty cycle, average flow rate was inversely associated with cut rate.ConclusionHigh-speed cut rate improved efficiency of vitreous aspiration.Translational RelevanceIncreased vitreous aspiration of dual-pneumatic, high-speed vitrectomy probes may improve the efficiency of current vitrectomy techniques, allowing surgeons to take advantage of the benefits of high cut rates without sacrificing flow rate.

The sphere of influence on surrounding tissue was greatest with large-gauge vitrectomy probes. This laboratory model indicated that small-gauge probes could be used to target specific tissues while minimizing the effects on adjacent tissue structures.