Torsional mode versus conventional ultrasound mode phacoemulsification - Randomized comparative clinical study

PURPOSE: To compare the intraoperative and short-term postoperative outcomes of cataract surgery performed with torsional mode and conventional ultrasound mode using the Infiniti Vision System (Alcon Laboratories). SETTING: Cataract Service, Zhongshan Ophthalmic Center, Sun-Yat-Sen University, Guangzhou, China METHODS: In this randomized comparative study, 525 eyes were assigned to phacoemulsification by torsional mode or conventional ultrasound (US) mode. The surgery was performed by an experienced Surgeon, and the outcomes were evaluated by an examiner who was masked to treatment assignments. Primary outcome measures were US time (UST), cumulative dissipated energy (CDE), and surgical complications. Patients were seen 1, 7, and 30 days after surgery. Postoperative outcome measures were the final best corrected visual acuity (BCVA) and the change in corneal clarity, central corneal thickness (CCT), and enclothelial cell count. RESULTS: The US group had 262 eyes and the torsional group, 263 eyes. All patients completed the follow-up visits. In the eyes with nucleus density grades of 1, 2, 3, and 4, the mean UST was 10.25 seconds +/- 7.4 (SD), 25.14 +/- 5.5 seconds, 36.45 +/- 8.3 seconds, and 61.44 +/- 17.8, respectively, in the US group and 8.32 +/- 6.8 seconds, 18.45 +/- 7.2 seconds, 29.48 +/- 12.4 seconds, and 48.39 +/- 20.3 seconds, respectively, in the torsional group (P <.001); the mean CDE was 1.25 +/- 0.5, 4.18 +/- 1.2, 8.59 +/- 6.5, and 16.51 +/- 9.6, respectively, in the US group and 0.94 +/- 0.3, 3.13 +/- 2.7, 7.47 +/- 12.6, and 14.08 +/- 8.3, respectively, in the torsional group (P <.001). At I day and 7 days, the mean BCVA was 0.23 +/- 0.12 logMAR and 0.00 +/- 0.10 logMAR, respectively, in the US group and 0.18 +/- 0.11 IogMAR and -0.08 +/- 0.05 logMAR, respectively, in the torsional group (P <.001). At 30 days, the mean BCVA was -0.10 +/- 0.07 logMAR and -0.12 +/- 0.06 IogMAR in the US group and the torsional group, respectively (P >.01). At I day and 7 days, the mean CCT was 625 +/- 80 pm and 568 +/- 37 pm, respectively, in the US group and 601 +/- 35 mu m and 559 + 40 pm, respectively, in the torsional group (P <.001). At 30 days, the mean CCT was 531 +/- 30 mu m in the US group and 529 +/- 39 tm in the torsional group (P >.01). At 7 days and 30 days, the mean central corneal enclothelial cell count was 2135 +/- 858 cells/mm(2) and 2084 +/- 527 cells/mm(2), respectively, in the US group and 2004 +/- 656 cells/mmyand 1953 +/- 615 cells/mm respectively, in the torsional group (P <.001). CONCLUSION: The torsional mode may provide more effective lens removal with a lower level of phacoemulsification time and energy.