long posterior ciliary artery

The long posterior ciliary artery is a branch of the ophthalmic artery, itself a branch of the internal carotid artery. There are typically two long posterior ciliary arteries, and they are involved in supplying blood to the choroid, ciliary body, and iris. Unlike the short posterior ciliary arteries, they travel a longer course through the sclera to reach anterior ocular structures.

The long posterior ciliary arteries pierce the sclera on either side of the optic nerve, near the equator of the eyeball. They travel forward within the suprachoroidal space—between the sclera and choroid—on the nasal and temporal sides of the eye, running toward the ciliary body and iris in the anterior segment.

The long posterior ciliary arteries are involved in supplying oxygenated blood to the ciliary body and iris, as well as contributing to the choroidal circulation. The ciliary body uses this blood supply for aqueous humor production and accommodation. The iris depends on these vessels for its vasculature and the pupillary sphincter and dilator muscles.

Ischemia of the long posterior ciliary arteries may be associated with conditions such as giant cell arteritis, systemic vasculitis, or atherosclerosis. Compromise of these vessels may be involved in anterior ischemic optic neuropathy or iris and ciliary body ischemia. Elevated intraocular pressure may also affect perfusion in these vessels.

The long posterior ciliary arteries can be assessed using fluorescein angiography or indocyanine green (ICG) angiography, which evaluates choroidal and anterior segment blood flow. Color Doppler imaging of the ophthalmic artery and its branches provides functional flow information. Clinical examination of the iris and ciliary region may also yield indirect evidence of their perfusion status.