Fluidics of Single and Double Blade Guillotine Vitrectomy Probes in Balanced Salt Solution and Artificial Vitreous

To assess the fluidics of double-vitreous cutter blade (DB) compared with single-blade (SB) guillotine with 23-, 25-, and 27-gauge vitrectomy probes. To assess flow characteristics and flow rates in viscous and viscoelastic fluids.

We used Particle Image Velocimetry to measure the flow field close to the tip of each cutter probe and we derived kinematic quantities of interest, such as kinetic energy and acceleration. We performed measurements both on a balanced salt solution (BSS) and on a viscoelastic artificial vitreous (AV).

The flow rate is significantly higher with DB than SB vitrectomy probes, for a given pumping pressure and cutting rate. The fluid flow observed is very different between BSS and AV tests.

The DB has more efficient fluidics than SB vitrectomy probe in all tested conditions. Fluid acceleration depends on the cutting frequency, especially in the case of measurements in AV. The flow rate strongly depends on the pressure and it is little affected by the cutting frequency, in a range of clinical interest. The 27-G DB produces flow rates similar to the 23- and 25-G SB, with significantly smaller acceleration. The flow induced in the AV is different from that in BSS and oscillates at different frequencies.

DB cutters prove to be more efficient in terms of lower acceleration for a given flow rate. The latter is mainly controlled by aspiration pressure and less by cut rates. The influence of vitreous rheology deserves further investigations.