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.