title: [Dynamic viscosity and corneal endothelial protection with Healonid, Healon GV, Provisc and Viscoat during phacoemulsification].
abstract: OBJECTIVE
  To demonstrate the utility of a viscoelastic substance which maintains high viscosity during phacoemulsification, we conducted a double study.
  
  
  METHODS
  We compared in vitro the corneal endothelial protection offered by Healon, Healon GV, Provisc and Viscoat after <<traumatic>> phacoemulsification. Eight samples of ten to fifteen freshly enucleated pig eyes were operated; the first four groups were the controls, whereas the other four tested the different viscous solutions. In parallel, we determined the rheologic properties of the four viscoelastic substances in a physicS laboratory. To measure the percentage of corneal endothelial cell damage, we used the Janus Green spectrometric technique.
  
  
  RESULTS
  Corneal endothelial cell damage averaged 31.67% in eyes in which no viscoelastic substance was used. Damage was 14.29% in specimens that received Healon, 12.85% with Healon GV, 2.48% in the Viscoat group and 15.43 in those that received Provisc. There is a significant difference (p <0.001) between the Viscoat group and all other samples. The values of the viscosity at different shear rates and the graph of viscosities as a function of shear rate of the four viscous solutions are given.
  
  
  CONCLUSIONS
  Viscoat has a very high dynamic viscosity at high shear rate. This property and a poor cohesion provide a better corneal endothelial protection during in vitro phacoemulsification.
authors.affiliation: C.M.C. Foch, Service d'Ophtalmologie, Suresnes Cedex.
authors.forename: C
authors.initials: C
authors.lastname: Bresciani
authors.forename: D A
authors.initials: DA
authors.lastname: Lebuisson
authors.forename: M
authors.initials: M
authors.lastname: Eveillard
authors.forename: J L
authors.initials: JL
authors.lastname: Grossiord
authors.forename: F
authors.initials: F
authors.lastname: Drupt
authors.forename: G
authors.initials: G
authors.lastname: Montefiore
mesh_terms: D000818:Animals; D004728:Endothelium, Corneal; D005069:Evaluation Studies as Topic; D006820:Hyaluronic Acid; D018918:Phacoemulsification; D012212:Rheology; D013053:Spectrophotometry; D014783:Viscosity
chemical_list: D006820:Hyaluronic Acid
vernacular_title: Viscosite dynamique et protection endotheliale corneenne du Healonid, du Healon GV, du Provisc et du Viscoat au cours de la phacoemulsification.