choriocapillaris

The choriocapillaris is the innermost vascular layer of the choroid, a dense sheet of capillaries located just external to Bruch’s membrane and the retinal pigment epithelium. It forms a single, highly perfused network that lies beneath the outer retina and provides its principal blood supply. The capillaries are fenestrated, permitting rapid exchange of nutrients, oxygen, and waste between the blood and the adjacent retinal tissues. The choriocapillaris is organized into a lobular network that follows the posterior pole and integrates with the surrounding choroidal vasculature.

Blood reaches the choriocapillaris from the short posterior ciliary arteries, passing through choroidal arterioles in Sattler’s layer and then into the capillary network. Venous drainage occurs through the vortex veins. The close proximity of the choriocapillaris to the outer retina supports the high metabolic demands of photoreceptors and the retinal pigment epithelium, contributing to retinal homeostasis and thermal regulation.

Clinical relevance: Alterations in choriocapillaris perfusion and dropout are associated with age-related macular degeneration and other choroidal pathologies. Noninvasive imaging techniques such as indocyanine green angiography and optical coherence tomography angiography are used to assess choriocapillaris perfusion and integrity, aiding in diagnosis and research into outer retinal diseases.