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E.D. Varnell, H.E. Kaufman, H.W. Thompson; Effect of Recombinant Human Hyaluronidase on Intraocular Pressure in Rabbits Following Injection of Viscoelastic Substances . Invest. Ophthalmol. Vis. Sci. 2005;46(13):798.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To measure the effect of recombinant human hyaluronidase on intraocular pressure in rabbits following injection of surgical viscoelastics. Methods: New Zealand white rabbits were acclimated to having their intraocular pressures measured by Tono–Pen. rHuPH20 was manufactured by Halozyme Therapeutics, provided in BSS and diluted on the morning prior to use to a solution of 25,000 USP Units/ml. The rabbits were anesthetized, and using a 30 g needle, 150 microliters of aqueous humor was removed through clear cornea. Through a second injection site, 100 microliters of either Healon or Viscoat was injected into the anterior chamber. One eye of an animal was injected with 50 microliters of BSS and the other with 50 microliters of hyaluronidase. Injections of viscoelastic were randomized, as were eyes injected with either the BSS or enzyme, and all intraocular pressure (IOP) measurements were made in a masked manner. IOP was measured with a Medtronics Tono–Pen at 1, 2, 4, 6, 8, 12, 24, and 48 hours after injection of the viscoelastic. Six rabbits were injected with Healon and six with Viscoat. Animals were provided buprenorphine analgesia. Treatment conformed to the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research and was approved by the LSUHSC IACUC. The data were analyzed separately for Viscoat and Healon. For each, IOP levels were analyzed as the outcome in a repeated measures analysis of variance and subsequent mean separation techniques that controlled the experiment–wise alpha level for the set of comparisons between treatment means. Results: After injection of Viscoat or Healon, the intraocular pressures rose rapidly, reaching peak pressures by approximately 4–6 hours. Twenty fours after injection of the viscoelastics, the pressures had returned to pre–injection levels. Intraocular pressure rises were significantly prevented by the hyaluronidase in both the Healon and the Viscoat injected eyes. Conclusions: This highly purified, recombinant human hyaluronidase prevents the elevated intraocular pressure caused by the injection of two commercially available surgical viscoelastics. This purified human derived material avoids the inflammatory immunogenic potential of preparations manufactured from animal sources.
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