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C. DeBoer, S. Fang, L. Chong, P. Bhadri, A. Rowley, J. Cicchella, D. Leung, M. McCormick, R. Kerns, M. Humayun; High-Speed Vitrectomy: The Next Generation of Instrumentation. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2210.
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© ARVO (1962-2015); The Authors (2016-present)
To explore flow characteristics of next generation high-speed cutters operating at speeds up to 6,000 cuts per minute (CPM).
A custom 20-gauge probe was developed for high-speed operation (6,000 CPM). Two duty cycles (50% and 65%) were used to check performance characteristics in water and in vitreous. The probe was operated at 200 mmHg aspiration at speeds ranging from 2,000 to 6,000 CPM. During in-vitro cutting, the weight of the resulting vitreous was measured two times per second with an Ohaus (Pine Brook, NJ) balance, while real time data was recorded with National Instruments LabView (Austin, TX) and converted into flow rates. Trials were conducted with the probe in vitreous (n=3) and in water (n=3). The results were analyzed using regression analysis, t-test, and confidence interval parameter. To analyze the interaction with vitreous, high-speed video of cutter tips in action was captured with a Dalsa (Waterloo, Ontario, Canada) 1M150 camera. Duty cycle was also measured as a function of speed with high-speed video analysis.
Higher speed corresponded with higher flow rates in vitreous at all cut speeds (0.0185 +/- 0.0052 ml/s at 2,000 CPM versus 0.0368 +/- 0.0009 ml/s at 6,000 CPM for the 50% duty cycle, p<0.05). However, at higher speed, water rates showed a slight decline (0.151 +/- 0.002 ml/s at 2,000 CPM versus 0.109 +/- 0.003 ml/s at 6,000 CPM for the 50% duty cycle, p<0.05). This data is different than previous measurements taken at lower speed (lower than 2,500 CPM) on commercial cutters. High-speed video of the cutter working at 2,000 CPM and 6,000 CPM visually demonstrates the difference in vitreous removal rates. At 2,000 CPM, clogging is observed in the cutter as vitreous enters. At 6,000 CPM clogging is less prevalent, thereby resulting in higher flow rates.
Vitreous removal trends observed at lower cut speeds are also present with high-speed cutting. Water trends demonstrate slight differences. This needs to be further investigated.
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