Efficacy and safety of enzymatic posterior vitreous detachment by intravitreal injection of hyaluronidase.

PURPOSE: To investigate the efficacy and safety of intravitreal injection of hyaluronidase in producing liquefaction resulting in a posterior vitreous detachment. METHODS: Fifteen young pigmented rabbits were randomized into 3 groups that received 5 (group 1), 10 (group 2), or 20 (group 3) IU of hyaluronidase. The fellow eyes were injected with a volumetric equivalent dose of balanced salt solution as control. The rabbits were followed for 9 weeks and examined for signs of ocular and retinal toxicity. The animals were then euthanized and their eyes were examined histologically. RESULTS: Biomicroscopic evaluation in all but one rabbit revealed no evidence of ocular toxicity. One rabbit showed evidence of vitreous traction on the retina with transient retinal elevation. Biomicroscopically and histologically, all rabbits in group 3 and four of five rabbits in group 2 had evidence of a posterior vitreous detachment. CONCLUSION: Intravitreal injection of hyaluronidase in doses of 10 IU or higher induces posterior vitreous detachment in rabbits over a period of 5 weeks. Intravitreal doses of 20 IU or less do not appear to affect the biomicroscopic morphology or function of ocular structures adversely. Injections of hyaluronidase, therefore, could be considered as an alternative or adjunct to conventional mechanical vitrectomy.