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Paulo E Stanga, Salvador Pastor, Isaac Zambrano, Paul Carlin; NEW PROTOTYPE OF ULTRASOUND HARMONICS VITRECTOR (UHV) FLUIDICS ANALYSIS: FIRST REPORT. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):385. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The liquefaction and excision of the vitreous body using low power ultrasound harmonics (UH) is a promising new alternative to pneumatic guillotine vitrectomy systems. The purpose of this study is to evaluate the effect of gauge size, percentage of ultrasound power (US) and aspiration settings on flow rate performance using a prototype ultrasonic harmonics vitrector (UHV). We compare our results using this new technology with those of a currently commercially available pneumatic guillotine vitrector.
Performance of the UHV (Bausch + Lomb, St. Louis, MO, USA) and currently commercially available pneumatic guillotine vitrector using 23G and 25G gauge needles (Stellaris PC® Vitrectomy system, Bausch + Lomb, St. Louis, MO, USA). Pre-determined aspiration levels (50, 100, 200, 300, 400, 500 and 600 mmHg), cut rates for guillotine vitrector (0, 500, 1000, 1500, 2000, 3000, 4000 and 5000 cuts per minute (CPM)) and percentages of US power for the 23G and 25G UHV needles (0, 10, 20, 30, 40, 50 %) were used in Balanced Salt Solution (BSS®) and porcine vitreous. Porcine eyes were obtained within 12-24h of slaughter and the anterior segment removed at the pars plana to allow for open-sky vitrectomy surgery of undiluted vitreous. The vials with BSS® and the sectioned eyes were weighed on a high-precision balance (high-speed (2 samples/s) weight scale precise to 0.0001g). Two independent observers performed six measurements of the mass of BSS® and the vitreous: before (n=3) and after (n=3) vitrectomy surgery. Results were converted to volume removed as a function of time-flow rate (ml/min), using the arithmetic mean of the weight calculations.
There was no vitreous flow at zero cut rates or US% (off) for both UH and pneumatic vitrectors. Needle gauge of UHV did not affect flow rate when used with either BSS® or vitreous. However, gauge size strongly affected flow rate when using the guillotine vitrector (p<0.01), both in BSS® and vitreous. Wall thickness of UHV needles did not affect flow rates neither in BSS® nor vitreous.
Flow rate is not affected by gauge of UHV needle for similar ports and vacuums and this could allow for the use of smaller gauge and port size, as well as lower infusion pressures than with a guillotine vitrector. These new findings demonstrate a promising new alternative to the currently commercially available technology for vitrectomy systems.
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