First Author: D.Abulon USA
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Some studies reported restricted aspiration with smaller diameter vitrectomy probes. To optimize instrument performance during vitrectomy, it is important to understand the impact of system settings on smaller gauge instruments. Previous research characterized 23-gauge vitreous flow rates up to 10,000 cuts per minute (cpm). This study assessed the performance of smaller instruments by measuring vitreous flow rates of 25-gauge dual-pneumatic probes under various duty cycle modes and high-speed cut rates up to 10,000 cpm.
In-vitro laboratory testing of porcine cadaver vitreous flow associated with small, 25-gauge vitrectomy probes.
Six 25+® gauge Advanced UltraVit® vitrectomy probes were tested using the CONSTELLATION® Vision System (Alcon Laboratories, Inc.). Each probe was evaluated at three duty cycle modes (ie, port biased open, 50% port open time, port biased closed), at various cut rates (ie, 2500, 5000, 7500, and 10,000 cpm), using 650 mmHg vacuum. Porcine cadaver eyes were harvested within 24 hours and vitreous was extracted immediately before testing. During simulated vitrectomy, an electronic balance (Mettler Toledo MS 2014S) measured the volume of aspirated vitreous during a 1 minute time frame. Average vitreous flow rates were calculated using the density of vitreous, change in weight, and duration of aspiration.
The 25-gauge vitreous flow rates associated with the biased-open mode increased from 2.72±0.34 to 2.83±0.27 as cut rate increased from 2,500cpm to 10,000 cpm. Vitreous flow rates associated with the 50% port open duty cycle increased from 2.19±0.23 cc/min to 2.84±0.27 cc/min as cut rates increased from 2,500 cpm to 10,000 cpm. In the biased-closed duty cycle mode, vitreous flow rates also increased from 1.89±0.31 cc/min at 2500 cpm to 2.78±0.15 cc/min at 10,000 cpm. With all three duty cycles, maximum vitreous flow rates were associated with the maximum cut rate of 10,000 cpm.
With small, 25-gauge instrumentation at 650 mmHg vacuum, maximum vitreous flow was observed at the maximum cut rate for all duty cycle modes. The 10,000 cpm cut rates of the dual-pneumatic high-speed vitrectomy probes may optimize vitreous aspiration.