Transverse vs torsional ultrasound: prospective randomized contralaterally controlled study comparing two phacoemulsification-system handpieces

Abstract

Kerry K Assil, Lindsay Harris, Jeannie Cecka Assil Eye Institute, Beverly Hills, CA, USA Purpose: To compare surgical efficiency and multiple early clinical outcome variables in eyes undergoing phacoemulsification using either transversal or torsional ultrasound systems.Setting: Assil Eye Institute, Beverly Hills, CA, USA.Design: Prospective, randomized, clinician-masked, contralaterally controlled single-center evaluation.Patients and methods: Patients seeking cataract removal in both eyes with implantation of multifocal intraocular lenses were randomly assigned to one of two treatment rooms for phacoemulsification with either a transverse ultrasound system or torsional handpiece system. The contralateral eye was treated at a later date with the alternate device. A total of 54 eyes of 27 patients having similar degrees of cataract, astigmatism, and visual potential were included. All operative data were collected for analysis, and patients were followed for 3 months after surgery.Results: Similar visual acuity was reported at all postoperative visits between the two groups. Mean phacoemulsification time and total power required were both significantly lower with the transverse system than with the torsional technique (P<0.05 for both). Similarly, mean total balanced salt solution used was significantly less with the transverse system vs torsional (P<0.05). Postoperative safety demonstrated significantly lower endothelial cell loss at 1 day and 1 month (P<0.05) with transverse vs torsional. Macular swelling was less at 1 week, 1 month, and 3 months with transverse vs torsional, although the difference did not achieve significance (P=0.1) at any single time point. Clinically detectable corneal edema was reported less frequently at all postoperative time points with the transverse system.Conclusion: The transverse ultrasound system was found to be possibly associated with less balanced salt-solution use, less phacoemulsification time, and less power required than the torsional phaco system. Postoperative data suggested that improved phaco efficiency may translate to a better overall safety profile for the patient. Keywords: phacoemulsification, transversal, torsional, cutting efficiency