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Bjorn Lundgren, Stina Nilsson; Evaluation Of Anterior Chamber Volume (acv) Restoration Capacity Of Ophthalmic Viscosurgical Devices (ovd) With Different Rheological Properties. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6234.
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© ARVO (1962-2015); The Authors (2016-present)
An OVD maintains the anterior chamber, protects the corneal endothelium and facilitates IOL implantation during cataract surgery. OVDs differ in rheologic and physicochemical properties due to concentration and molecular weight of the rheological active molecule of the OVD. The purpose of this evaluation was to objectively study the performance of OVDs with different rheological characteristics regarding ACV restoration capacity.
Eyes from newly slaughtered pigs were used. The ACV was measured using the Pentacam Scheimpflug camera (Oculus). Through a 30G needle on a 1 ml syringe, all aqueous humor was withdrawn and through the same incision Healon in the volumes of 150, 200 and 250 µl were injected in order to validate the ACV estimation by the Pentacam. The weight of the injected OVD and the ACV measurement were evaluated using correlation analysis. For product comparison a 2.75 mm scleral-corneal incision was made and all aqueous humor was removed and 250 µl of OVD was injected. ACV measurements were obtained before incision and after OVD injection. OVD brands tested were Healon 5 (viscoadaptive), Healon GV and Healon (cohesives), Vitrax II (dispersive), all four hyaluronan based (AMO), and Ocucoat (HPMC based dispersive, Bausch & Lomb Inc). Six eyes were tested for each OVD. The ability to restore the ACV was evaluated by comparing ACV values and injected OVD volumes. The Kruskal-Wallis test was used to evaluate differences between the products.
The validation showed a good correlation between ACV measurement and injected OVD volume (r=0.8). The ACV restoration capacity differed significantly between the tested OVDs. The Healon5 OVD and Healon GV OVD showed mean retention capacities of 91 and 89% respectively. The figures for Healon OVD and Vitrax II OVD were 81 and 83% respectively. For the HPMC based Ocucoat OVD the mean ACV retention capacity was 40%. These results are also significantly correlated to the zero shear viscosity of the OVDs.
The Pentacam camera can be used to evaluate the ACV restoration capacity of OVDs. The ACV restoration capacity is positively correlated to the zero shear viscosity of an OVD.
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