Torsional Power and Tip Shape Greatly Change Irrigation Flow Feeding Rate

Background: It is important to maintain intraocular pressure during cataract surgery. When the intraocular pressure sharply drops during phacoemulsification, it is important to ensure a compensatory maximum fluid supply. To the best of our knowledge, this is the first study presenting the maximum irrigation flow supply using an ultrasonic tip shape and torsional power setting. Methods: The weight of BSS PLUS 500 ejected during torsional oscillation fitted with a mini-tip or balanced tip and nano sleeve with IOP set at 20 mmHg (IOP20) or 40 mmHg (IOP40) was measured. The weight of the BSS ejected from the sleeve over 3.0 s (15 measurements taken at 200-ms intervals) was measured to calculate the irrigation flow feeding rate. Measurements were made four times at each torsional power setting (TP). Results: With a balanced tip, the irrigation flow rate rose as TP was increased, whereas, at 60% or 90% TP, the irrigation flow rate markedly decreased. With the mini-tip, the irrigation flow rate remained relatively stable, up to 60% or 80% TP but decreased dramatically at higher power settings. Compared with IOP20, the irrigation flow rate increased by 1.21- to 1.28-fold with the balanced tip and by 1.28- to 1.41-fold with the mini-tip at IOP40. At IOP20, the irrigation flow rate was higher with the mini-tip at 0% and 5% TP but equal to or higher with the balanced tip at TP of ≥10%. At IOP40, the irrigation flow rate with the mini-tip was equal to or higher than that with the balanced tip at all TP. Conclusions: The irrigation flow rate tends to vary with changes in TP and tip shape.