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Improving vitreous cutter performance through the understanding of fluidics

Session Details

Session Title: Vitreoretinal Surgery I

Session Date/Time: Thursday 26/09/2013 | 11:00-12:30

Paper Time: 11:00

Venue: Hall 3 (Level 0)

First Author: T.Rossi ITALY

Co Author(s):    G. Querzoli   G. Angelini   C. Malvasi        

Abstract Details

Purpose:

Purpose of present paper is to study the fluidics around vitreous cutter probes by means of Particle Image Velocimetry (PIV) in order to test several blade and port design to ascertain which allow the most efficient and safe vitrectomy. Both Venturi and peristaltic pump have been considered and various combinations of cut rate and aspiration tested for each port design.

Setting:

Experimental in vitro study

Methods:

PIV analysis has been conducted with a high speed camera set at 1000 frames per second and 23G cutter probes immersed in BSS, egg albumen and porcine vitreous. Three different blade designs (the regular one (R) and 2 original pending patent shapes that will be disclosed during the meeting, named A and B) have been tested and significant fluidics parameters measured: fluidic velocity field, acceleration, variation of acceleration (jerk) and flow rate. Acceleration and jerk positive and negative peaks and flow rates were compared by means of paired t-test, while overall curve behavior was compared through CHI-squared of the Area under the Curve (AUC). The significance has been set at the 0.05 level in all cases.

Results:

Blade B resulted in significantly higher flow rate than A and R in all media. R rated worse that the innovating designs. Velocity fields also differed significantly among different probe designs as well as fluid acceleration did. Acceleration was lowest with the B blade than R in vitreous and albumen while rated lower than R in BSS and similar to A blade. Acceleration variation (jerk) also behaved similarly.

Conclusions:

Blade B yielded lower acceleration and better flow rate than, respectively, A and R in both BSS and alcumen and porcine vitreous. Acceleration of fluids around the cutter port is of paramount importance in the generation of retinal traction during vitreous removal and an objective indicator of cutter safety. Flow rate, on the other hand, speaks for the efficacy of cutters. A better understanding of fluidics behavior in response to blade motion and cutter suction is the key to the development of a new generation of vitrectomy machines.

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