There are two circulations of the eye: the retinal (in the retina) and uveal, supplied in humans by posterior ciliary arteries, originating from the ophthalmic artery (a branch of the internal carotid artery).The Ocular Circulation The arteries of the uveal circulation, supplying the uvea and outer and middle layers of the retina, are branches of the ophthalmic artery and enter the eyeball without passing with the optic nerve. The retinal circulation, on the other hand, derives its circulation from the central retinal artery, also a branch of the ophthalmic artery, but passing in conjunction with the optic nerve."Sensory Reception: Human Vision: Structure and function of the Human Eye" vol. 27, p. 174 Encyclopædia Britannica, 1987 They branch in a segmental distribution to end arterioles and not anastomoses. This is clinically significant for diseases affecting choroidal blood supply. The macula responsible for central vision and the anterior part of the optic nerve are dependent on choroidal blood supply. The structure of choroidal vessels can be revealed by optical coherence tomography, and blood flow can be revealed by Indocyanine green angiography, and laser Doppler imaging.Puyo, Léo, Michel Paques, Mathias Fink, José-Alain Sahel, and Michael Atlan. "Choroidal vasculature imaging with laser Doppler holography." Biomedical optics express 10, no. 2 (2019): 995-1012.
