Persistent fetal intraocular vasculature in the European ferret (Mustela putorius): clinical and histological aspects.

Abstract

To describe the clinical and histological appearance of persistent fetal intraocular vasculature in a colony of ferrets. Design Prospective study. Eighty-six European ferrets (Mustela putorius). Procedure Both eyes of 76 genetically related progeny and 10 breeding, adult, colony-raised ferrets were studied using a slit lamp biomicroscope and an indirect ophthalmoscope. Ferret progeny were examined after eyelid opening at 5-6 weeks of age, and at 12 months of age. After euthanasia, globes were enucleated and examined histologically. Persistent fetal intraocular vasculature was evident in 21 progeny ferrets at 5-6 weeks of age and in three mature progenitor ferrets. Clinical appearance of diminutive vasculature was characterized by focal remnants of the posterior tunica vasculosa lentis, muscae volitantes, and an occluded hyaloid artery extending from the optic papilla and terminating in the anterior vitreous body. Extensive persistent vasculature was characterized by a perfused hyaloid artery, vasa hyaloidea propria and posterior tunica vasculosa lentis, posterior cortical and capsular cataract, and proliferation of fibrovascular tissue along the posterior lens capsule. Fetal vasculature persisted in 7 of 21 progeny ferrets at one year of age and in three progenitor ferrets. Results of histologic examination showed persistence of the hyaloid vasculature, proliferation of retrolental fibrovascular tissue with osseous metaplasia, posterior capsular and cortical cataract, and occasional retinal detachment. Persistent fetal intraocular vasculature in ferrets appears similar clinically and histologically to persistent fetal intraocular vasculature reported in humans and dogs. The ferret may be a suitable animal model for vasculogenic mechanisms of persistent fetal intraocular vasculature and for evaluating vasoinhibitory growth factors and angiostatic test compounds.