EFFICACY OF HYALURONIDASE IN REDUCING INCREASES IN INTRAOCULAR-PRESSURE RELATED TO THE USE OF VISCOELASTIC SUBSTANCES

Objective: To evaluate the efficacy of hyaluronidase in preventing inc reases in intraocular pressure related to injections of hyaluronan-con taining viscoelastic substances. Methods: Twenty-five white rabbits we re divided into 5 groups. In groups 1 through 4, 0.15 mL of aqueous hu mor was removed and replaced with 0.10 mt of a viscoelastic substance in both eyes. Additionally, 10 units of hyaluronidase (0.05 mt) was in jected in the anterior chamber of the right eye, whereas the left eye was injected with a volumetrically equivalent dose of balanced saline solution. Viscoelastic substances tested were Healon and Healon GV (Ph armacia Gt Upjohn, Kalamazoo, Mich),Viscoat (Alcon Laboratories, Fort Worth, Tax), and Ocucoat (Storz Ophthalmics, Clearwater, Fla). In grou p 5, right eyes were injected with 10 units of hyaluronidase and the l eft eyes were treated with balanced saline solution. Results: After in jections of viscoelastic substance, intraocular pressure rose rapidly, reaching a peak at approximately 46 hours after injection and returni ng to preinjection levels within 24 hours. Hyaluronidase significantly decreased intraocular pressure when used with Healon, Healon GV, and Viscoat, but not with Ocucoat. When injected in the absence of viscoel astic, hyaluronidase appeared to decrease intraocular pr this result w as not statistically significant. Conclusions: Injections of hyaluroni dase into the anterior chamber of rabbits effectively prevent increase s in intraocular pressure induced by hyaluronan-containing viscoelasti c substances. This effect may be related to the ability of hyaluronida se to cleave hyaluronan moieties.