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

Objective To describe the clinical and histological appearance of persisten t fetal intraocular vasculature in a colony of ferrets. Design Prospective study. Animals studied Eighty-six European ferrets (Mustela putorius). Procedure Both eyes of 76 genetically related progeny and 10 breeding, adul t, colony-raised ferrets were studied using a slit lamp biomicroscope and a n indirect ophthalmoscope. Ferret progeny were examined after eyelid openin g at 5-6 weeks of age, and at 12 months of age. After euthanasia, globes we re enucleated and examined histologically. Results Persistent fetal intraocular vasculature was evident in 21 progeny ferrets at 5-6 weeks of age and in three mature progenitor ferrets. Clinica l appearance of diminutive vasculature was characterized by focal remnants of the posterior tunica vasculosa lentis, muscae volitantes, and an occlude d hyaloid artery extending from the optic papilla and terminating in the an terior vitreous body. Extensive persistent vasculature was characterized by a perfused hyaloid artery, vasa hyaloidea propria and posterior tunica vas culosa lentis, posterior cortical and capsular cataract, and proliferation of fibrovascular tissue along the posterior tens capsule. Fetal vasculature persisted in 7 of 21 progeny ferrets at one year of age and in three proge nitor 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 occasion al retinal detachment. Conclusions Persistent fetal intraocular vasculature in ferrets appears sim ilar clinically and histologically to persistent fetal intraocular vasculat ure 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 compound s.