Cutter Velocities of Two Vitrectomy Probes: Dual Pneumatic and a Single Pneumatic Drive With Spring Return

Abstract

 

Purpose

 

This study was conducted to compare the cutter velocities of 2 different vitrectomy probes: a dual pneumatic drive (DPD), in which a pneumatic drive pulse drives the probe both open and closed, and a single pneumatic drive with a spring return (SPDSR), in which a pulse drives the probe closed but a spring opens the port. The purpose was to determine the effect of these 2 designs on the cutter velocities.

 

Methods

 

Two different types of probes were compared: DPD (Constellation® UltraVit®, Alcon Laboratories, Inc.) and SPDSR (Stellaris PC, Bausch & Lomb). Six each of 23- and 25-gauge (G) probes were tested. High-speed video of the cutter movement through the probe port was captured at 25,000 frames per second. All probes were run at 1500, 2500, and 5000 cuts per minute (cpm). The cutter movement was analyzed from the captured video frames to calculate the cutter closing and opening velocities.

 

Results

 

See Table 1.

 

Conclusions

 

The SPDSR cutter closing and opening velocities were highest at 2500 cpm. The DPD cutter closing and opening velocities were highest at 5000 cpm. For all probes, the closing velocities were higher with the 25G probe compared to the 23G probe. Optimal tissue shearing may be associated with high cutter velocities. In this study, the 25G DPD cutter in the Shave mode at 5000 cpm generated the highest closing velocities Md potentially the beat shearing capabilities.

 

 

Table 1. Results: Closing and Opening Cutter Velocities.

 

Keywords: 762 vitreoretinal surgery • 688 retina • 763 vitreous