[Dynamic viscosity and corneal endothelial protection with Healonid, Healon GV, Provisc and Viscoat during...

To demonstrate the utility of a viscoelastic substance which maintains high viscosity during phacoemulsification, we conducted a double study.

We compared in vitro the corneal endothelial protection offered by Healon, Healon GV, Provisc and Viscoat after <> 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.

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.

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.