DYNAMIC VISCOSITY AND CORNEAL ENDOTHELIAL PROTECTION WITH HEALONID(R), HEALON GV(R), PROVISC(R) AND VISCOAT(R) DURING THE PHACOEMULSIFICATION

Purpose To demonstrate the utility of a viscoelastic substance which m aintains high viscosity during phacoemulsification, we conducted a dou ble study. Methods We compared in vitro the corneal endothelial protec tion offered by Healon(R), Healon GV(R), Provisc(R) and Viscoat(R) aft er << traumatic >> phacoemulsification. Eight samples of ten to fiftee n freshly enucleated pig eyes were operated; the first four groups wer e the controls, whereas the other four tested the different viscous so lutions. In parallel, we determined the rheologic properties of the fo ur viscoelastic substances in a physic laboratory. To mesure the perce ntage of corneal endothelial cell damage, we used the Janus Green spec tometric technique. Results Corneal endothelial cell damage averaged 3 1.67 % in eyes in which no viscoelastic substance was used Damage was 14.29 % in specimens that received Healon(R) 12.85 % with Healon GV(R) 2.48 % in the Viscoat(R) group and 15.43 in those that received Provi sc(R). There is a significant difference (p < 0.001) between the Visco at(R) group and all other samples. The values of the viscosity at diff erent shear rates and the graph of viscosities as a function of shear rate of the four viscous solutions are given. Conclusion Viscoat(R) ha s 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.