Abstract
Purpose :
To 1) measure the vitreous flow rates of 25-Gauge (Ga) dual-cutting, 20,000 cuts per minute (cpm) vitrectomy probes at various vacuum settings and 2) identify vacuum settings required to match vitreous flow performance of previous generation single-cutting 10,000 cpm probes.
Methods :
A precision balance (Mettler Toledo, XS with reliability of 0.1 g/ 1g, Greifensee, Switzerland) reported the mass of vitreous in an open beaker. During 25+® Ga Advanced UltraVit® and HyperVit ® vitrectomy probe aspiration of vitreous, a LabVIEW VI program calculated the volumetric flow rate using the change in weight, duration of aspiration, and vitreous density. Testing was evaluated at vacuum settings ranging from 50 to 650mmHg with intervals of 50mmHg in the Core duty cycle mode. For each vitrectomy parameter combination, flow was measured at least 3 times and averaged. Average flow rates and standard deviations were reported for different probes under different vacuum settings. A Welch’s statistical T-Test compared the flow rate of HyperVit® vitrectomy probes at maximum cut rate (20,000cpm) to the flow rate of previous generation Advanced UltraVit® vitrectomy probes at maximum cut rate (10,000cpm). A statistical significance level of p<0.05 was used.
Results :
Vitreous flow increased with increasing vacuum. With vacuum settings ranging from 50 mmHg to 650 mmHg, flow rate for 25 Ga probes ranged from 0.25±0.05 cc/min to 2.77±0.22cc/min. The vitreous flow rate of 10,000 cpm probes at maximum cut rate and 650mmHg vacuum was 2.76± 0.25 cc/min. If using a 20,000 cpm dual-cutting probe, the vacuum setting of 550 mmHg was required to achieve similar flow (2.77± 0.22 cc/min; p=0.943). To match the flow of 25 Ga single-cutting 10,000cpm probes in the Core duty cycle, maximum cut rate, and 650 mmHg vacuum, the dual-cutting 20,000cpm probes required 15.4% lower vacuum than the previous generation probes.
Conclusions :
The 25 Ga, dual-cutting 20,000 cpm probes have more efficient aspiration than previous generation single-cutting 10,000 cpm probes. With dual-cutting probes, lower vacuum settings are required to achieve vitreous flow similar to previous generation, single cutting probes.
This is a 2020 ARVO Annual Meeting abstract.