Vascular changes in the posterior eye segment of secondary angle-closure glaucoma: Cause or consequence?

Background: To study the role of choroidal and retinal vessels in the pathology of secondary angle-closure glaucoma. Methods: DBA/2NNia and non-glaucomatous C57BL/6J mice over the age range 2-20 months were investigated. Corrosion cast preparations of the vasculature were studied using scanning electron microscopy. Whole mounts of the retina and choroid were stained enzyme-histochemically for NADPH diaphorase as an indicator for nitric oxide synthase activity. Semi- and ultra-thin sections of the posterior eye segment were performed and evaluated. Results: DBA/2NNia mice showed loss of choroidal pigmentation and a decrease in choriocapillary density already at 4 months of age. In animals 9 months and older, a decrease of choroidal NADPH-diaphorase positive nerve fibers was evident. The retinal vasculature showed only mild changes in NADPH-diaphorase staining, even in the oldest animals. The ultrastructural appearance of the retinal vessels was similar in both mouse strains and for all ages investigated. Conclusions: Choroidal changes in the DBA/2NNia mouse are similar to that seen in other glaucoma models. The lack of retinal vasculature changes in adult and senescent DBA/2NNia mice suggests a normal blood supply of the retina during the progress of secondary angle-closure glaucoma in these animals.