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Bjorn Lundgren, Stina Nilsson; Objective evaluation of Ophthalmic Viscosurgical Device (OVD) removal using the Pentacam Scheimpflug camera. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6736.
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© ARVO (1962-2015); The Authors (2016-present)
OVDs are essential tools during cataract surgery in order to stabilize the anterior chamber and to protect delicate ocular tissues. At the end of the surgical procedure it is important to remove the OVD in order to avoid postoperative intraocular pressure spikes. Over the years OVDs with different viscoelastic properties have been developed in order to meet the need of different surgical techniques. The purpose with this study was, in an objective way, assess the ease of removal of OVDs differing in viscoelastic properties.
Eyes from newly slaughtered pigs were used. For product comparison a 2.75 mm scleral-corneal incision was made and 200 µl of a fluorescein stained OVD was injected. An image of the anterior chamber (AC) was captured using the Pentacam HR camera (Oculus) after injection, after 20 seconds of Irrigation/Aspiration and after complete removal of the OVD. The OVD brands tested were Healon5 (viscoadaptive), HealonGV, Healon and Amvisc plus (cohesives), Healon Endocoat, Viscoat, and Ocucoat (dispersives). Ten eyes were tested for each OVD. The amount of OVD left after 20 seconds was subjectively evaluated using a scale of 0, <25, <50, <75, or <100% of OVD left in the AC. For comparison of complete removal the time needed was used as evaluation parameter. The Kruskal-Wallis test was used to evaluate differences between the products (p<0.05).
After the 20 second evaluation all cohesive products had been eliminated from the AC while Healon5 OVD and the dispersive products still remained. For these brands complete mean removal time was 90 s (Viscoat), 66 s (Healon Endocoat), 52 s (Healon5), and 44 s (Ocucoat). This is in line with the clinical impression that dispersive products are more difficult to remove from the eye. The difference between Viscoat OVD and Healon Endocoat OVD was statistically significant.
The Pentacam camera can be used for objective visualization and assessment of the ease of OVD removal. The overall removal time is based on the viscoelastic characteristics of the OVDs, where cohesive OVDs are easier to remove than viscoadaptive OVDs, which is easier to remove than dispersive OVDs. Of all OVD brands tested Viscoat had the longest time for complete OVD removal and Amvisc Plus the shortest.
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