title: Effect of hydrodynamic parameters on corneal endothelial cell loss after phacoemulsification.
abstract: OBJECTIVE
  To evaluate the effect of power, vacuum, and flow rate on endothelial cell loss after phacoemulsification.
  
  
  METHODS
  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.
authors.affiliation: Department of Ophthalmology and Ophthalmic Research Center, Labbafinejad Medical Center, Shahid Beheshti University, Tehran, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Baradaran-Rafii
authors.forename: Mohsen
authors.initials: M
authors.lastname: Rahmati-Kamel
authors.forename: Medi
authors.initials: M
authors.lastname: Eslani
authors.forename: Victoria
authors.initials: V
authors.lastname: Kiavash
authors.forename: Farid
authors.initials: F
authors.lastname: Karimian
mesh_terms: D000368:Aged; D002452:Cell Count; D004728:Endothelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D019654:Lens Implantation, Intraocular; D008297:Male; D008875:Middle Aged; D018918:Phacoemulsification; D011184:Postoperative Period; D011446:Prospective Studies; D013396:Suction; D013997:Time Factors; D014065:Tonometry, Ocular; D014618:Vacuum; D014792:Visual Acuity