Viscoelastics in ophthalmosurgery

Ophthalmic viscosurgical devices (OVDs) entered clinical practice at the end of 20th century. OVDs are pharmacologically inactive, clear, highly viscous and elastic fluids that have both the properties of gels and solids. Their properties depend on molecular weight and concentration which are the determinants of OVD behavior in surgery. OVDs are classified based upon their behavior in surgery. The first classification distinguished dispersives (with lower viscosity) and cohesives (higher viscosity). 1 million Daltons have been used as a dividing line between a cohesive and dispersive agent. The subsequent development of viscoadaptives (Healon5) and higher viscosity dispersives (DisCoVisc) required the classification to be revised. This novel classification includes Cohesion-Dispersion Index (CDI). The paper reviews current OVD classification and the properties of different OVDs. OVDs are primarily used in cataract surgery to protect corneal endothelium from the direct contact with lens fragments and irrigation fluid, to maintain a deep anterior chamber and to keep iris lens diaphragm backward, to dilate the pupil, to prevent anterior capsule flap from curling, to dissect anterior and posterior synechias, to separate lens nucleus from the cortex and capsule (i.e., to perform viscodissection), to facilitate nuclear rotation in the capsular bag, to fill anterior chamber and capsular bag, and to flatten capsular bag. Beginning from 1980, OVDs are used in glaucoma surgery to maintain anterior chamber depth following trabeculectomy, thus lowering the incidence of hypotony, anterior chamber shallowing, and choroidal detachment. In addition, OVDs are used in choroidal detachment surgery. Most papers describe the injection of sodium hyaluronate. Finally, OVDs are used to dilate Schlemm's canal in the course of viscocanalostomy, to perform viscogoniosynechiolysis in anterior chamber angle closure, and to protect corneal endothelium when applying cytostatic agent at the surgical site.

вискоэластики, вязкость, факоэмульсификация, трабекулэктомия, гипотония, отслойка сосудистой оболочки, OVDs, viscosity, phacoemulsification, trabeculectomy, hypotony, choroidal detachment

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