PURPOSE To compare the effects of fluidic parameters on the central corneal thickness (CCT), corneal endothelium, and anterior segment inflammation after phacoemulsification with longitudinal ultrasound. SETTING Iladevi Cataract & IOL Research Center, Ahmedabad, India. METHODS In this prospective randomized patient- and examiner-masked study, consecutive patients with age-related cataract were randomly assigned to Group 1 (low fluidic parameters: aspiration flow rate 25 cc/min; bottle height 70 cm and 90 cm; vacuum <or=400 mm Hg) or Group 2 (high fluidic parameters: aspiration flow rate 40 cc/min, bottle height 90 cm and 110 cm; vacuum <or=650 mm Hg). The rate of change in CCT and endothelial cell density (ECD), the incidence of anterior segment inflammation, and corneal clarity were compared between groups. RESULTS The mean change in CCT from preoperatively to 1 day postoperatively was -6.49% +/- 2.7% in Group 1 and -13.44% +/- 4.3% in Group 2 and from preoperatively to 7 days, -1.74% +/- 1.3% microm and -5.55% +/- 4.3%, respectively (both P<.001). There was no statistically significant difference in the rate of change in ECD between groups from preoperatively to 3 months postoperatively (4.67% +/- 0.15% versus -5.22% +/- 2.84% (P = .45). Anterior chamber flare, cells, and corneal clarity at 1 day were significantly better in Group 1 than in Group 2. CONCLUSION Low fluidic parameters led to a lower increase in CCT 1 day and 7 days postoperatively, decreased anterior segment inflammation at 1 day, and yielded clear corneas.