Origin
- The ophthalmic artery originates as the first major branch of the internal carotid artery immediately after it emerges from the cavernous sinus.
- The origination usually happens near the anterior clinoid process.
Course
- Entry into Orbit: The ophthalmic artery then travels forward and enters the orbit via the optic canal, along with the optic nerve. It usually courses inferolateral to the optic nerve within the optic canal.
- Course in the Orbit: Upon entering the orbit, the ophthalmic artery generally takes a sinuous or ‘S’ shaped course, moving initially medial and then turning superior and lateral.
- Medial Turn: After emerging from the optic canal, the ophthalmic artery initially turns medially, passing under the optic nerve.
- Superior Turn: It then turns superiorly, passing over the optic nerve.
- Lateral Turn: As it continues to course anteriorly, it moves laterally, running along the superior border of the orbit in the extraconal space.
- Terminal Branches: Towards the anterior part of the orbit, the ophthalmic artery gives off several terminal branches, including the supraorbital and dorsal nasal arteries, which leave the orbit to supply the forehead and nose.
Branches & Supply
The ophthalmic artery supplies nearly all the structures in the orbit, as well as some structures in the nose, face, and meninges:
Orbital Branches
- Lacrimal artery: Typically, the first branch, supplies the lacrimal gland, lateral eyelids, and conjunctiva.
- Supraorbital artery: Supplies the forehead and scalp.
- Posterior ethmoidal artery: Supplies the ethmoid and sphenoid sinuses and the nasal cavity.
- Anterior ethmoidal artery: Supplies the ethmoid sinuses, frontal sinus, and nasal cavity.
Ocular Branches
- Central retinal artery: Supplies the inner retinal layers.
- Short posterior ciliary arteries: Supply the choroid and outer retinal layers.
- Long posterior ciliary arteries: Supply the ciliary body and iris.
Branches Exiting the Orbit
- Palpebral arteries: Supply the eyelids.
- Frontal artery: Supplies the forehead.
- Nasal artery: Supplies the nose.
Relations
- Superior: Superior to it lie the frontal nerve and the levator palpebrae superioris muscle.
- Inferior: Lies on the medial wall of the orbit.
- Medial: Medially, it is related to the trochlear nerve.
- Lateral: Optic nerve in the optic canal.
Normal Variants
- Origin: In rare cases, the ophthalmic artery may arise from the middle cerebral artery instead of the internal carotid artery.
- Course: The ophthalmic artery typically travels under the optic nerve, but in some individuals, it may travel above the nerve (superoptic).
- Branching pattern: There can be considerable variation in the branching pattern and the number of branches given off by the ophthalmic artery.