We connected 23-gauge (G) probes mounting a regular guillotine blade (RB) or a double bevel, 100% duty cycle Twedge blade (TB) to the R-Evolution CS vitrectomy machine console (Optikon 2000, Inc., Rome, Italy) equipped with a double Venturi/peristaltic pump and tested under typical surgical settings. Cutters were secured vertically and probe tip immersed in balanced salt solution (BSS; Alcon, Fort Worth, TX, USA). To allow fluid motion detection by means of PIV, BSS was seeded with triamcinolone crystals (Kenakort; Brystol Squibb-Meyers, New York, NY, USA) passed through a 40-μm filter.
A 532-nm green laser light slit was shed directly onto the cutter tubing, 10 mm proximal to the hand piece and the camera focused inside the transparent tubing, 90° away from the light-source, as described previously.
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