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RESEARCH PRODUCT

Osmolality of various viscoelastic substances: comparative study.

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Abstract Purpose To determine the osmolality of various viscoelastic substances. Setting Department of Ophthalmology, Johannes Gutenberg-University, Mainz, and Institute for Medical Device Testing, Memmingen, Germany. Methods The analysis was carried out according to the European Pharmacopoeia by means of a calibrated osmometer using the freezing-point depression method. Each syringe was analyzed as a duplicate analysis. Results Mean osmolalities (mOsmol/kg) of the sodium hyaluronate viscoelastic substances were Allervisc® 299; Allervisc® Plus 307; Amvisc® Plus 335; AMO Vitrax® 284; Biolon® 279; Dispasan® 311; Dispasan® Plus 314; Healon® 295; Healon GV® 312; Healon®5 322; HYA-Ophtal® 376; Microvisc® 313; Microvisc® Plus 341; Provisc® 307; Rayvisc® 312; Viscoat® 340; Visko® 296; Visko® Plus 319. Mean osmolarities of the hydroxypropyl methylcellulose viscoeslatic substances were Adatocel® 278; HPMC Ophtal® L 358; HPMC Ophtal® H 360; La Gel® 317; OcuCoat® 309; Visco Shield® 376. Conclusion There were significant differences in osmolality among viscoelastic substances, which may explain the differences in corneal thickness after cataract surgery. A viscoelastic substance with an osmolality of 305 mOsmol/kg or slightly higher is preferable, especially in patients with a compromised corneal endothelium.