Performance Comparison of High-Speed Dual-Pneumatic Vitrectomy Cutters during Simulated Vitrectomy with Balanced Salt Solution

Abstract

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 25+-gauge 5000-cpm probes; UltraVit 23-gauge and enhanced 25+-gauge 7500-cpm probes; n = 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.

Conclusions: The 7500-cpm probes offer greater control and customization compared with 5000-cpm probes under certain experimental conditions. At maximum cut rates, performance of 7500-cpm probes was similar to that of 5000-cpm probes, suggesting that 7500-cpm probes may be used without sacrifice of flow rate and IOP stability.

Translational relevance: Customization of vitrectomy parameters allows greater surgeon control during vitrectomy and may expand the usefulness of vitrectomy probes.

Keywords: 23-gauge vitrectomy; 25-gauge vitrectomy; 5000 cpm; 7500 cpm; Constellation Vision System; aspiration; cut rate; duty cycle; flow rate; intraocular pressure; vitrectomy.

Figure 1.

Instrument setup. BSS, balanced salt solution; DAQ, data acquisition.

Figure 2.

Flow rate (A) and IOP (B) comparison for the Constellation Vision System with enhanced 25-gauge 5000- and 7500-cpm probes. Each data point represents the average of six measurements. IOP, intraocular pressure.

Figure 3.

Flow rate (A) and IOP (B) comparison for the Constellation Vision System with 23-gauge 5000- and 7500-cpm probes. Each data point represents the average of six measurements. IOP, intraocular pressure.