The branches of the ophthalmic artery comprise the entire arterial supply to the eye. Most commonly the ophthalmic artery branches off of the internal carotid artery, distal to the cavernous sinus, then travels through the optic canal. The ophthalmic artery has multiple branches which separate into two categories: orbital branches and optical branches. The orbital arteries include the ciliary arteries, retinal artery, and muscular arteries.
The structure of eye arteries is similar to that of arteries throughout the body. Arteries are considered rigid vessels, in comparison to veins. They consist of tunica intima, media, and externa. Arteries in the eye are also susceptible to damage by glycosylation reactions and plaque deposition in patients with diabetes and hypertension which are two common risk factors for ocular pathology.
Eye development takes place from week 3 to week 10. Ocular blood vessels originate from mesenchyme. First, optic grooves grow outward, forming optic vesicles. The optic vesicles attach to the forebrain via the optic stalk which later becomes the optic nerve. On the inferior surface of the optic vesicles and stalk a C-shaped fissure, known as the choroidal fissure, forms. The choroidal fissure serves as the entrance point for blood vessels. Through this fissure, the hyaloid artery can access the growing lens. By week 10, the distal portion of the hyaloid artery disintegrates, and the proximal portion remains as the central retinal artery.
Persistent fetal vasculature can lead to impairment in vision or even blindness. Ocular examination findings vary depending on degree and area of vessel persistence.
Ocular lymphatics correlate more closely with the venous system. Findings show that ocular structures differ in their lymphatic makeup. The retina is lymphatic free, the lacrimal glands are lymphatic rich, and the iris is lymphatic inducible.
The ophthalmic artery and its branches travel near the optic nerve. The central retinal artery runs in the dural sheath of the optic nerve. The central retinal artery also has a sympathetic nerve plexus, called the nerve of Tiedemann, that surrounds it.
Ciliary muscles and the six extrinsic eye muscles receive vascular supply by branches of the ophthalmic artery. Long posterior ciliary arteries provide blood to the ciliary muscles. The superior, lateral, medial and inferior rectus muscles receive blood from anterior ciliary arteries. Each rectus muscle receives supply from two anterior ciliary arteries, except the lateral rectus which receives blood from only one artery. The lateral muscular artery also supplies the lateral and superior rectus as well as the superior oblique muscle. The medial muscular branch supplies the inferior and medial rectus and inferior oblique muscles.
Most commonly the ophthalmic artery originates from the internal carotid artery. However, in 2 to 3% of individuals, the ophthalmic artery has a different origin. It has been found to arise from the anterior cerebral artery, middle cerebral artery, posterior communicating artery or the middle meningeal artery. 
The most common variant is that of the ophthalmic artery originating from the middle meningeal artery. During embryologic development, the stapedial artery, an orbital branch of the middle meningeal artery enters the orbit through the canal of Hyrtl to supply the developing eye. Anastomoses between the ophthalmic artery and middle meningeal artery may persist.
Knowledge of the ophthalmic artery branches and origin is of significant importance in regards to treatment for head and neck tumors or persistent epistaxis. Determination of the ophthalmic artery origin must occur before middle meningeal artery embolization. If the ophthalmic artery originates from the middle meningeal artery, its occlusion will lead to severe visual impairment or blindness.
The ophthalmic artery branches distal to the cavernous sinus then enters the optic canal. This short intracranial course is of surgical importance as it is the site of surgical intervention for ophthalmic artery aneurysms. Surgical treatment for ophthalmic artery aneurysms should be done cautiously due to proximity to the optic nerve, optic canal, and clinoid process.
Central retinal artery occlusion (CRAO) is a stroke of the eye. The central retinal artery is an end artery; hence, its occlusion presents with sudden, painless monocular vision loss. CRAO is an ophthalmologic emergency. Individuals with carotid artery disease and atherosclerotic plaque deposition are at highest risk. Emboli are the most common etiology of CRAO. On ocular examination, patients may have a cherry-red spot (90%), retinal opacity in the posterior pole (58%), optic disk pallor (39%), retinal arterial attenuation (32%), optic disk edema (22%), intra-arterial emboli (20%), and/or cattle trucking (19%). On fluorescein angiography, delayed filling time of the affected vessel may be present. Treatment includes acute reperfusion of the central retinal artery and prevention of future vascular ischemic events. Carotid duplex is the recommendation when a patient presents with painless, monocular vision loss because of the high risk of another ischemic event.
The definition of amaurosis fugax is transient vision loss, often monocular and painless. The pathophysiology is similar to that of CRAO: occlusion or stenosis within the internal carotid circulation. Similar to CRAO, on ocular examination one may find cholesterol plaques (Hollenhorst plaques).
Retinoblastoma is a childhood ocular tumor. One treatment method is intra-arterial chemotherapy. Selective occlusion of eye arteries has proven to have less systemic side effects in comparison to systemic chemotherapy.
The choriocapillaris supplies the outer layer of the retina. Included in receiving blood supply from the choroid is the fovea centralis, the area of the highest cone concentration in the retina.
The ophthalmic artery has branches that enter the eye (optic branches) and orbital branches. The orbital branches include:
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