Cerebrovascular Disease
John W. Scadding, Nicholas A. Losseff in Clinical Neurology, 2011
The brain is supplied by two internal carotid arteries and two vertebral arteries. The internal carotid arteries begin in the neck at the bifurcation of the common carotid artery and ascend intracranially. The first branch of the internal carotid artery is the ophthalmic artery. The former then bifurcates into the anterior and middle cerebral arteries. Both anterior and middle cerebral arteries give off other branches and deep penetrating vessels. The anterior cerebral artery supplies among other structures much of the ‘leg’ representation of the cortex. The middle cerebral artery supplies the ‘arm’ representation, some of the ‘leg’ representation, and the speech areas in the dominant hemisphere or the areas of spatial awareness in the non-dominant hemisphere. The penetrating vessels supply the deeper portions of the hemisphere, including the internal capsule, basal ganglia and visual radiation.
Eye Microcirculation
John H. Barker, Gary L. Anderson, Michael D. Menger in Clinically Applied Microcirculation Research, 2019
The eye receives its blood supply from the ophthalmic artery, which enters the orbita through the optic canal. Inside the orbita, anterior ciliary arteries branch off and follow the extraocular muscles to their insertion anteriorly in the sclera. Here, the main vessel penetrates the sclera to supply the anterior segment of the eye, including the ciliary body and the iris, while smaller branches leave to supply the perilimbal conjunctiva. The posterior ciliary arteries branch from the ophthalmic artery in a variable number just behind the eyeball, with two long vessels branching to the equatorial choroid, and about ten shorter vessels branching to the posterior choroid. After penetration of the sclera, the choroidal vessels branch and end in lobules with large fenestrated capillaries that are in close proximity to the retinal pigment epithelium.1 Structural evidence suggests that choroidal lobules in the periphery are supplied by a central arteriole and are drained by venoles arranged peripherally at the lobule, whereas the reverse arrangement exists in the posterior pole.2 The choroid has the largest blood perfusion in the body per unit tissue weight, and the resulting small oxygen extraction (5%) ensures a high ambient oxygen concentration in the outer retina supplied by this system.3 The choroidal circulation is regulated autonomously with sympathetic innervation from the superior cervical ganglion and parasympathetic innervation from the ciliary and the pterygopalatine ganglions.4
Ocular Blood Flow and Metabolism
Neil T. Choplin, Carlo E. Traverso in Atlas of Glaucoma, 2014
The ophthalmic artery (OA) supplies both major ocular vascular beds: the retinal and uveal systems. Its major branches include branches to the extraocular muscles, the central retinal artery, and the posterior ciliary arteries (Figure 12.1). The uveal system, which supplies blood to the iris, ciliary body, and choroid, is supplied by one to five posterior ciliary arteries (PCA). They emerge from the ophthalmic artery in the posterior orbit. Short posterior ciliary arteries (SPCAs) penetrate the sclera surrounding insertion of the optic nerve (Figure 12.2). These vessels supply the peripapillary choroid as well as the majority of the anterior optic nerve. Some SPCAs course, without branching, through the sclera directly into the choroid; others divide within the sclera to provide branches to both the choroid and the optic nerve. Often, a noncontinuous arterial circle exists within the perineural sclera, the circle of Zinn–Haller. This structure is formed by the convergence of branches from the SPCAs. The circle of Zinn–Haller provides blood for various regions of the anterior optic nerve, the peripapillary choroid, and the pial arterial system.
Giant cell arteritis
Published in Postgraduate Medicine, 2023
Kristie Pepper
The most serious complication of GCA remains permanent visual loss which can occur in up to 20% of patients before glucocorticoid therapy initiation [66]. In a study of patients with biopsy-proven GCA, patients with ocular involvement were older, with a lower ESR and were less likely to have a headache or other systemic symptoms of giant cell arteritis than those without ocular involvement [67]. Two proposed reason for this variability in ocular involvement are the lack of classic symptoms of GCA making patients less likely to be referred for temporal artery biopsy and treatment in a prompt fashion and that those with a highly inflammatory response (elevated inflammatory indices) had more circulating IL-6 which has angiogenic properties and could counteract the arteritic ischemia of GCA [66]. GCA has a predilection for the ophthalmic artery and its branches most importantly the posterior ciliary arteries and the central retinal artery. The posterior ciliary arteries perfuse the choroid which nourishes the photoreceptors in the outer third of the retina and the optic nerve head. The central retinal artery provides blood to the inner two third of the retina including the retinal ganglion cells – the axons forming the optic nerve. The ophthalmic artery in addition to these two branches, also provides blood to the extraocular muscles and the vasa nervorum of the ocular motor nerves [68]. Vision changes in GCA have been described as a result of each of these vessels, in addition, vessels in the vertebrobasilar circulation can become involved which supplies circulation to the occipital lobe.
Visual Loss after Platelet-rich Plasma Injection into the Face
Published in Neuro-Ophthalmology, 2020
Emely Z. Karam, Alexander Gan, Rafael Muci Mendoza, Edwing Martinez, Evlyn Perez
In order to understand the pathophysiology when embolisation causes blindness it is important to remember the anatomy. The central retinal artery (CRA) is a branch of the ophthalmic artery. The ophthalmic artery is connected to the supraorbital, supratrochlear, dorsal nose, and lacrimal arteries that supply the glabellar region, forehead, nose, and lacrimal gland respectively. These arteries are part of the internal carotid artery system. The facial, angular, infraorbital, and temporal superficial arteries that supply the nasolabial and nasojugal folds, the mid-face, and temple respectively, are part of the external carotid artery system. There are anastomoses between the two systems. The mechanism by which dermal fillers induce blindness could be by direct injury to the globe or from accidental high-pressure injection of a fillers into the blood vessel causing retrograde local or distal emboli. Also, the nature of the material filler could be related. Thick, cohesive substances should theoretically be less likely to embolise, unlike oily liquids (fat injections, silicone oil) or particulate solutions (steroid suspensions).4 Also, the particle size and the amount of filler injected per injection site could also affect the risk of embolisation.9,10
Imaging-based Assessment of Choriocapillaris: A Comprehensive Review
Published in Seminars in Ophthalmology, 2023
Rohan Bir Singh, Tatiana Perepelkina, Ilaria Testi, Benjamin K. Young, Tuba Mirza, Alessandro Invernizzi, Jyotirmay Biswas, Aniruddha Agarwal
The arterial blood supply to the choroid predominantly arises from the ophthalmic artery branches from the internal carotid artery.19 The ophthalmic artery branches into two posterior ciliary arteries (in 48% of eyes) or three posterior ciliary arteries (in 38% of eyes). The posterior ciliary branches into the medial and lateral posterior ciliary arteries, showing different anatomical variations. The long posterior ciliary arteries arise from the medial and lateral posterior ciliary arteries, whereas the short posterior ciliary arteries arise from other branches of the posterior ciliary arteries. These branches are further divided into choroidal arterioles, which ultimately branch and segmentally feed into the choriocapillaris lobule.17 The recurrent branches of the long posterior and anterior ciliary artery supply the anterior choriocapillaris, and the short posterior ciliary arteries primarily supply the posterior choriocapillaris.
Related Knowledge Centers
- Cavernous Sinus
- Eye
- Internal Carotid Artery
- Meninges
- Optic Canal
- Optic Nerve
- Orbit
- Nose
- Face
- Anterior Clinoid Process