Effect of hydrodynamic parameters on corneal endothelial cell loss after phacoemulsification.

PURPOSE To evaluate the effect of power, vacuum, and flow rate on endothelial cell loss after phacoemulsification. SETTING Labbafinejad Medical Center Medical Center, Tehran, Iran. METHODS In a prospective randomized clinical trial, phacoemulsification was performed in 2 groups (high vacuum and low vacuum) with 3+ nuclear sclerosis. The stop-and-chop technique was used with the Sovereign machine. Machine parameters during the chop stage were vacuum 400 mm Hg in the high-vacuum group and 200 mm Hg in the low-vacuum group and flow rate, 40 cc/min and 20 cc/min, respectively. Endothelial cell density preoperatively before and 1, 6, and 12 weeks postoperatively were compared. RESULTS Each group comprised 30 eyes. The mean US power was 9.2% +/- 4.3% (SD) in the low-vacuum group and 13.1% +/- 4.6% in the high-vacuum group (P = .001) and the mean phaco time, 1.28 +/- 1.0 minutes and 0.88 +/- 0.6 minutes, respectively (P = .04). Total US energy and total fluid consumed were similar between groups. After 12 weeks, the mean endothelial cell loss was 9.0% +/- 4.0% in the low-vacuum group and 9.6% +/- 4.6% in the high-vacuum group (P = .6). There was a relationship between total US energy and endothelial loss (P<.001); however, total fluid volume was not a significant predictor (P = .19). CONCLUSIONS Vacuum level did not have a significant effect on total US energy or total fluid consumed during phacoemulsification. There was a strong relationship between total US energy and endothelial cell loss but not between total infused fluid and endothelial cell loss.