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The ophthalmic artery is the first branch of the internal carotid artery. It comes off just distal to the cavernous sinus. The ophthalmic artery gives off many branches, which supply the orbit, meninges, face, and upper nose. When the ophthalmic artery is occluded, it can compromise vision. The ophthalmic artery comes off the internal carotid artery on the medial side of the anterior clinoid process and traverses anteriorly through the optic canal and just lateral to the optic nerve.[rx][rx][rx]
The following are branches of the ophthalmic artery:
- The first branch of the ophthalmic artery is the central retinal artery that runs in the dura mater of the optic nerve. It then moves further along and supplies the inner layers of the retina.
- The second and the largest branch of the ophthalmic artery is the lacrimal artery. It also enters the orbit and traverses along the superior edge of the lateral rectus muscle. It supplies the eyelids, lacrimal gland, and conjunctiva.
- The ophthalmic artery gives off several posterior ciliary arteries that pass through the sclera and supply the posterior uveal tract. Because the posterior ciliary vessels are end vessels, sudden occlusion can produce infarction in the region of the choroid.
- The ophthalmic artery also gives off the inferior and superior muscular vessels that supply the extraocular muscles. The supraorbital artery is also a branch of the ophthalmic artery and passes through the supraorbital foramen to supply the skin of the forehead and Levator palpebrae muscle.
- Other branches of the ophthalmic artery include the ethmoid arteries, medial palpebral vessels, and terminal branches.
The orbital arteries include the ciliary arteries, central retinal artery, and muscular arteries.[rx]
- Long Posterior Ciliary Arteries – The long posterior ciliary arteries (1 to 2) travel near the optic nerve and pierce the posterior sclera to supply the choroid and ciliary muscle before joining the major arterial circle of the iris.[rx] The major arterial circle of the iris distributes branches to the iris and ciliary body.
- Short Posterior Ciliary Arteries – The number of short posterior ciliary arteries vary per individual, often ranging between 6 to 12 arteries that branch off the ophthalmic artery as it crosses the optic nerve medially. These arteries supply the ciliary processes and optic disk. The arterioles branching from the posterior ciliary arteries supply the choroid. The perpendicular terminal arterioles supply choriocapillaris, the blood supply to Bruch’s membrane and outer retina.[rx]
- Anterior Ciliary Arteries – There are seven anterior ciliary arteries that branch from the muscular arteries and run with the extraocular muscles. The anterior ciliary arteries supply the rectus muscles, conjunctiva, and sclera before joining the long posterior ciliary arteries to form the major arterial circle of the iris.[rx] Each rectus muscle receives its vascular supply from two anterior ciliary arteries, except the lateral rectus which receives blood supply from only one anterior ciliary artery.
- Central Retinal Artery – It is the first branch of the ophthalmic artery. It is a terminal branch supplying the inner layer of the retina, and its occlusion can cause sudden visual loss. It travels inferiorly and within the optic nerve sheath to supply the inner two-thirds of the retina. The artery further divides into superior and inferior arcades, which form the blood-retina barrier.
- Muscular branches – The two muscular branches of the ophthalmic artery that supply extraocular muscles include the medial and lateral muscular branches. The medial artery being larger than the lateral muscular branch.
When there is occlusion of the ophthalmic artery, it can result in an ischemic syndrome. Amaurosis fugax is a condition associated with temporary, painless loss of vision due to either an embolic phenomenon or hypoperfusion. Emboli to the ophthalmic artery usually originate from the carotid artery bifurcation. One may visualize Hollenhorst bodies (a.k.a., Eickenhorst plaques) in the retina during fundoscopic evaluation. When there is a sudden, painless loss of vision in one eye, it is recommended that one obtain a duplex ultrasound of the neck to assess the carotid artery for atherosclerotic plaques.[rx][rx][rx]
The ophthalmic artery is intimately associated with the optic nerve (e.g., Cranial Nerve II). Additional important neurovascular structures in proximity to the ophthalmic artery include the following structures:
- Lacrimal Nerve (Cranial Nerve Va)
- Frontal Nerve (Cranial Nerve Va)
- Trochlear Nerve (Cranial Nerve IV)
- Superior Division of the Oculomotor Nerve (Cranial Nerve IIIs)
- Nasociliary Nerve (Cranial Nerve Va)
- Inferior Division of the Oculomotor Nerve (Cranial Nerve IIIi)
- Abducens Nerve (Cranial Nerve VI)
- Ganglionic Branches (from Pterygopalatine Ganglion to Maxillary Nerve)
- Infraorbital Nerve (Cranial Nerve Vb)
- Zygomatic Nerve (Cranial Nerve Vb)
- Superior Ophthalmic Vein
- Inferior Ophthalmic Veins
- Infraorbital Vein
- Infraorbital Artery
As mentioned previously, the ophthalmic artery continues medially as the superior and inferior muscular branches. These important branch vessels originate either directly from the ophthalmic artery or from a separate trunk that subsequently divides into the superior and inferior branches. These branches provide blood supply to the extraocular muscles.