Ultrasound power and irrigation volume in different lens opacity grades: comparison of femtosecond laser-assisted cataract surgery and conventional phacoemulsification.

OBJECTIVES: To compare the amount of ultrasound energy and irrigation volume in conventional phaco-emulsification cataract surgery versus femtosecond laser-assisted phacoemulsification at different nuclear-cortical cataract grades. METHOD: This was a prospective, consecutive, investigator-masked nonrandomized parallel cohort study. Patients were divided into 4 groups (Phaco1, Phaco2, Femto1 and Femto2) according to the surgical technique (conventional phacoemulsification [Group Phaco] or femtosecond laser-assisted cataract surgery [Group Femto]) and the Lens Opacity Classification System III (LOCS) grade (LOCS<11 [group 1] or LOCS >= 11 [group 2]). The measured outcomes were effective phacoemulsification time (EPT), indicating the ultrasound energy, and balanced salt solution (BSS) use, indicating the irrigation volume, to indirectly estimate the damage to the corneal endothelium caused by the cataract surgery. RESULTS: A total of 160 eyes from 109 patients were included: 87 eyes in Group Phaco, 73 eyes in Group Femto, 76 eyes in group 1 and 84 eyes in group 2. The EPT mean in Femto1 was 53% less (2.73 +/- 1.88, 0.1 to 8.65) than that in Phaco1 (5.80 +/- 2.86) (p=0.00) and in Femto2 (8.38 +/- 9.32) was 33% less than that in Phaco2 (12.55 +/- 8.38) (p=0.00). No significant differences in mean LOCS grades between the Phaco1 (8.21 +/- 1.44) and Femto1 (7.90 +/- 1.90) groups (p=0.73) or between the Phaco2 (13.15 +/- 2.55) and Femto2 (12.72 +/- 2.18) groups (p=0.95) were found. There were no significant differences in the mean BSS use between the Phaco1 (55.73 +/- 12.45) and Femto1 (59.37 +/- 10.93) groups (p=0.48) or between the Phaco2 (64.34 +/- 21.00) and Femto2 (65.71 +/- 17.60) groups (p=0.47). CONCLUSIONS: Compared to conventional phacoemulsification at different nuclear-cortical cataract grades, femtosecond laser-assisted cataract surgery provides an EPT reduction but does not influence the BSS use.