Choroidal Perfusion Abnormalities
The choroid has arterial supply from approximately 20 short posterior ciliary arteries and 2 anterior ciliary arteries. A network of branching arterioles distributes the blood throughout the choroid in a segmental fashion (Fig 9-7), ultimately leading to the choriocapillaris, and helps reduce the blood pressure as well. Although the vessels in the choriocapillaris exhibit relatively uniform patterns in any given region of the eye, the pressure gradients imposed by the feeding arterioles and draining venules establish a lobular perfusion pattern. Abnormalities in choroidal blood flow can be divided into several main categories based on the underlying disease process.
Figure 9-7 Diagram of the choroidal distribution of the short posterior ciliary arteries (PCAs) and long PCA branches arising from the temporal (lateral) PCA, and their watershed zones. Details of the branches from the medial PCA are not indicated. Dashed circle indicates the macular region.
(Used with permission from Hayreh SS. Submacular choroidal vascular pattern: experimental fluorescein fundus angiographic studies. Albrecht Von Graefes Arch Klin Exp Ophthalmol. 1974;192:181–196.)
In arteritic diseases such as giant cell arteritis (Fig 9-8) or granulomatosis with polyangiitis (formerly, Wegener granulomatosis) (Fig 9-9), inflammatory occlusion can cause sectoral areas of nonperfusion. Fluorescein or ICG angiography is typically performed in cases in which an arteritic cause of vision loss is suspected, because flow defects in the choroid are often undetected by ophthalmoscopy alone.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.