Role of the phaco tip surface

In his article reporting the results of a new prototype phacoemulsification tip with internal grooves (threaded tip), Watanabe1 showed that the threaded tip can amplify the cavitation effect and that intensification of cavitation gives a higher phacoemulsification effect. We have also investigated the role of the phaco tip when ultrasound (US) energy with an ultra-speed video recording system is applied by analyzing the stroke motion and the surface constitution before and after surgery. Based on our data and the frames of the videos, we assume that the shape of the phaco tip correlates to sections where the deterioration effect of cavitation is seen. This suggests that generation of the turbulence waves also depends on the tip design. In 2005, we described a technique for visualizing fluid turbulence and cavitation created by a US phaco tip and suggested that cavitation was involved in fragmentation of the nucleus.2 The study by Zacharias3 indicates that there is no relationship between cavitation and phacoemulsification power; moreover, he found that cavitation does not improve cutting function. Watanabe often references Zacharias’ work, often to support his own work, but attempts to contradict it if we consider the conclusion expressed above. Another consideration to evaluate is related to the fact that grooves create more cavitation. This is not a positive and safe result if the tissue damage effect and the dispersion of metal fragments in the anterior chamber are considered. Clinical studies show that cavitation may play a role in decreasing endothelial cells.2 and 4 The application of high-intensity US energy in the aqueous media can generate acoustic cavitation with the concomitant generation of free radicals and sonoluminescence, a phenomenon in which electronically excited species cause the emission of a light flash. It can also cause localized high pressure and temperature elevation.2 All these factors can cause tissue damage. Nevertheless, we strongly believe that the grooves, as designed by Watanabe, provide traction and mechanical adherence that could give the user a feeling of less chatter and can improve gripping capacity. In conclusion, we consider Watanabe’s study interesting and innovative and think that future studies should consider the potential role of the change of the tip surface to increase the gripping adherence and to reduce the chattering effect of the phaco tip.