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T. G. Chu, D. C. Buboltz; Comparison of Aqueous Flow Rates With Two Commercially Available Vitrectomy Systems. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3609.
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Aspiration flow is an important aspect of vitreoretinal surgery. Limited flow through first generation 25-gauge probes led some surgeons to believe 25-gauge technology was unsuitable for difficult surgical procedures, such as complex tractional retinal detachments seen in diabetic retinopathy. Conversely, the ability to purposely restrict flow may potentially improve safety when working near detached retina. This study investigates in vitro flow rates from two vitrectomy systems under a wide variety of surgical settings.
Balanced salt solution was infused at 30 mmHg into a closed-globe model eye system. Two vitrectomy systems were tested: the Millennium Microsurgical System (Bausch & Lomb, Inc.) with the Millennium Vitrectomy Enhancer (MVE), and the Constellation Vision System (Alcon). Six probes each of 20-, 23-, 25-, and 25+-gauge sizes were tested (per availability) across a range of vacuum from 50 to 650 mmHg and across a range of cut rates, from 500 cuts per minute (cpm) up the maximum available cut rate for each system. The Constellation Vision System was tested in 3 duty cycle modes.
With the MVE system, and the Constellation Vision System in its "core" duty cycle mode, flow rate decreased as cut rate increased matching the known trends for decrease in port duty cycle with increase in cut rates. For these systems, maximum flow with 25-gauge probes occurred at 500 cpm, and was 10.6 +/- 0.2 ml/min with the MVE system at maximum vacuum, and 14.1 +/- 0.9 ml/min for 25+-gauge probes with the Constellation Vision System in "core" duty cycle mode at maximum vacuum. For the Constellation Vision System in "shave" duty cycle mode, flow rates increased as cut speed increased. The MVE did not have a duty cycle setting comparable to the "shave" mode. For the Constellation Vision System in "50/50" duty cycle mode, flow rates were essentially constant across the range of cut speeds.
The Constellation Vision System with the 25-ga probe had higher flow rates compared to the other vitrectomy system. The duty cycle control capability of the Constellation Vision System allowed additional means to control the flow rate at various cut rates. This.may enhance surgeon control during difficult vitrectomy procedures.
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