choroidal

Choroidal is an adjective relating to the choroid, the vascular layer of the eye that lies between the retina and the sclera. It is part of the uveal tract and plays a key role in nourishing the outer retina and the retinal pigment epithelium.

Anatomy and structure: The choroid consists of three vascular layers from inside to outside: the choriocapillaris, a dense network of capillaries closest to the retina; Sattler’s layer, containing medium-sized vessels; and Haller’s layer, composed of larger vessels. The layer contains melanocytes that contribute to pigment and light absorption, helping to reduce stray light and protect retinal tissues. The choroid is highly vascular and has a high blood flow relative to its size.

Blood supply and drainage: Blood is supplied primarily by the short and long posterior ciliary arteries, feeding the choroidal circulation. Venous drainage occurs through vortex veins into the ophthalmic venous system. Autonomic nerves provide some regulation of blood flow and vessel tone.

Function and clinical relevance: The choroid supplies oxygen and nutrients to the outer retina, including photoreceptors, and helps maintain retinal temperature and metabolic homeostasis. It also participates in interfacial processes with the retinal pigment epithelium. Clinically, choroidal changes are involved in conditions such as choroidal neovascularization in age-related macular degeneration, central serous chorioretinopathy, inflammatory choroiditis, and choroidal tumors or metastases. Imaging and evaluation of the choroid are important in diagnosing and managing these conditions.