Proprietary or commercial disclosures are listed after the references.

Purpose: To analyze the difference between the behavior of semicircular (balanced) and bent (mini) tips at 20 incremental torsional power settings. Setting: Tsukazaki Hospital, Himeji, Japan. Design: Experimental study. Methods: Using an ultra-high-speed video camera HPV-X2, the 2 tips during torsional oscillation were recorded, comparing tip behavior at power settings from 5% to 100% by tracking points 1 to 5 (tip end and at 1325, 2650, 3975, and 5035 μm from the tip end). Results: Both tips increased their amplitude widths, drawing an S-curve at all points as the torsional power setting was increased, reaching their upper limits from 70% to 90% torsional power. At all 20 power settings, both tips showed significantly different amplitudes (all P < .01), and the difference of the amplitude increased as the power setting increased. Although, at points 1 and 3, the balanced tip amplitude was nearly 1.5 times larger than the mini tip amplitude, the amplitude difference was 10 μm or less at points 2 and 4. At point 5, the mini tip amplitude was at least 3 times more than the balanced tip amplitude. Conclusions: The amplitude does not increase proportionally and varies markedly with the tip shape on reaching the upper limit, suggesting that a higher power setting might not contribute greatly to nuclear fragmentation. The balanced tip might cause greater damage to surrounding tissues if it is inserted at approximately 3 mm from the wound site. To obtain maximum shaft stability using the balanced tip, it is important to insert at least 5 mm.

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.