Cataract surgery involves breaking up and removing the natural lens with a phacoemulsification (phaco) device, then replacing the natural lens with an artificial lens. Phaco handpieces and settings can be changed to achieve various goals. Although phaco is very safe, the process can put the cornea at risk of irreparable damage. One of the risk factors is the length of time and the energy used during phacoemulsification. Therefore, it is in the best interest of the surgeon to optimize settings for efficient removal of the natural lens. In this study, we compared the efficiency of longitudinal and transversal handpieces. Pig lenses soaked in formalin were used to replicate a human natural lens with a cataract. Efficiency was measured by the time taken to separate the lenses into two pieces using a process called grooving. The findings in this study by Wilkinson et al are important for determining which handpiece is most efficient for grooving.
Cataractous lenses were simulated by exposing porcine lenses to formalin for 2 hours. A total of 120 lenses were analyzed at various power settings on both longitudinal and transversal handpieces. Twenty trials each were performed with power set to 25%, 50%, and 75% on both handpieces. A Whitestar Phaco Handpiece System was used to provide longitudinal power, and a Whitestar Signature Ellipsis Handpiece provided transversal power. Lenses were placed within a plastic chamber and grooved by an investigator blinded to settings. A second investigator recorded times and adjusted settings. The Whitestar Signature Pro phaco system was used for grooving.
There was no significant difference in grooving times between the longitudinal and transverse handpieces at any power setting (P > 0.05). There was a significant decrease in grooving times when comparing the 25% power setting with the 75% power setting for the transversal handpiece (P=0.021).
At each power setting, the longitudinal and transversal handpieces on the Whitestar Signature Pro phaco system produced similar results. For each respective handpiece, there is a trend in decreased grooving times for higher power settings, which demonstrates increased efficiency. The transversal handpiece had a statistically significant decrease in grooving times at increasing power settings. Thus, the transversal handpiece may be more affected by changes in power than the longitudinal handpiece. Grooving efficiency is an important attribute during phaco. The duration of phaco and the amount of dissipated energy during phaco increase the likelihood of damage to the corneal endothelium. More power typically increases efficiency; however, increased power may also increase adverse effects caused by chatter and excess delivered energy. Therefore, the goal of phaco settings should be to find an optimal power setting with sufficient power to minimize duration of phaco without increasing power to the point of excessive chatter that may nullify the benefits of the higher power.
In conclusion, grooving time does not aid in selection between transversal and longitudinal phaco using the Whitestar Signature Pro system. Surgeon preference would appear to be more important in choosing the ultrasound mode used during the grooving step of cataract surgery.
Source: Wilkinson et al; Clinical Ophthalmology 2023:17 191–195
https://doi.org/10.2147/OPTH.S391928