Blood supply and drainage

• Summary
• Ophthalmic artery
• Orbital branches of the ophthalmic artery
• Lacrimal artery
• Supraorbital artery
• Posterior ethmoidal artery
• Anterior ethmoidal artery
• Medial palpebral artery
• Optical branches of the ophthalmic artery
• Long posterior ciliary artery
• Short posterior ciliary artery
• Anterior ciliary artery
• Central retinal artery
• Veins
• Ophthalmic veins
• Central retinal vein
• References
• Author(s)

Summary

The blood supply to the eye is mainly from the ophthalmic artery, which is a branch of the internal carotid artery. The drainage system of the eye involves the ophthalmic vein and the central retinal vein.

Ophthalmic artery

The ophthalmic artery is a branch of the internal carotid artery. It gives off orbital branches and optical branches.

Orbital branches of the ophthalmic artery:

• Lacrimal
• Supraorbital
• Posterior ethmoidal
• Anterior ethmoidal
• Medial palpebral

Optical branches of the ophthalmic artery:

• Long posterior ciliary artery
• Short posterior ciliary artery
• Anterior ciliary artery
• Central retinal artery

We will go through each of these arteries in turn.

Orbital branches of the ophthalmic artery

Lacrimal artery

This artery travels with the lacrimal nerve and supplies the lacrimal gland. The terminal branches of the artery also supply the eyelid and conjunctiva. It branches into the lateral palpebral arteries (which anastomose with the medial palpebral arteries).

Supraorbital artery

The supraorbital artery supplies part of the orbit, forehead and scalp. It passes through the supraorbital foramen and supplies the upper eyelid, frontal sinus, levator palpebrae superioris and part of the scalp.

Posterior ethmoidal artery

The posterior ethmoidal artery enters the nasal cavity through the posterior ethmoid canal and supplies the posterior ethmoidal sinuses, as well as entering the skull to supply the meninges.

Anterior ethmoidal artery

The anterior ethmoidal artery passes through the anterior ethmoidal foramen along with the nasociliary nerve into the middle and anterior air cells and also the frontal sinus. The artery also provides meningeal branches to supply the dura mater. There are also nasal branches that supply part of the dorsum of the nose.

Medial palpebral artery

The medial palpebral artery anastomoses with the lateral palpebral arteries (branches from the lacrimal artery) to supply the eyelid. The medial palpebral artery has two branches (superior and inferior) which supply the upper and lower eyelids respectively.

Optical branches of the ophthalmic artery

Long posterior ciliary artery

The long posterior ciliary arteries run anteriorly on both sides of the eyeball between the sclera and choroid. They supply the choroid and ciliary muscle and then merge to form the major arterial circle of the eye around the iris, then run inwards to form the minor arterial circle. Thus they also supply the iris.

Short posterior ciliary artery

The short posterior ciliary arteries supply the choroid. Each eye has around 6-12 short posterior ciliary arteries. They run between the sclera and choroid and also give off smaller branches that supply the optic disc by forming an arterial ring called the circle of Zinn-Haller.

Anterior ciliary artery

The anterior ciliary artery supplies the iris. There are 7 anterior ciliary arteries per eye. They terminate in the major arterial circle of the eye that surrounds the eyelid. The medial, inferior and superior rectus each receive two branches of this artery to supply these muscles, and the lateral rectus receives a single branch to supply it.

Central retinal artery

This is the main branch of the ophthalmic artery. It supplies the retina and parts of the optic nerve. The central retinal artery is a terminal artery, meaning that it does not form any anastomoses. It travels in the optic nerve and divides into the following branches:

• Superior branch
• Inferior branch
• Nasal branch
• Temporal branch

In diabetic retinopathy, haemorrhages and aneurysms can form in this artery and its branches.

Veins

Ophthalmic veins

The superior ophthalmic vein travels parallel to the ophthalmic artery. The superior ophthalmic vein is usually the largest and principal vein.

The inferior ophthalmic vein runs over the surface of the inferior rectus muscle. It may divide into two branches. One branch passes through the inferior orbital fissure. The other branch passes through the superior orbital fissure.

These ophthalmic veins drain into the cavernous sinus.

Central retinal vein

This is the main pathway of retinal venous drainage. The central retinal vein travels in the optic nerve and drains blood from the capillaries of the retina. It drains into either the superior ophthalmic vein or into the cavernous sinus directly.

An occlusion of the central retinal vein can lead to restriction in blood supply (ischaemia) and/or swelling (oedema). This can lead to severe damage to the retina, leading to loss of vision.

References

1. Kiel, Jeffrey W. Anatomy. Morgan & Claypool Life Sciences, 2010. www.ncbi.nlm.nih.gov, https://www.ncbi.nlm.nih.gov/books/NBK53329/.
2. Hayreh, S. S. ‘Orbital Vascular Anatomy’. Eye, vol. 20, no. 10, Oct. 2006, pp. 1130–44. www.nature.com, https://doi.org/10.1038/sj.eye.6702377.
3. ‘Muscles, Nerves, and Blood Vessels of the Eyes - Eye Disorders’. MSD Manual Consumer Version, https://www.msdmanuals.com/en-gb/home/eye-disorders/biology-of-the-eyes/muscles-nerves-and-blood-vessels-of-the-eyes. Accessed 27 June 2022.

Author(s)

Dr Abhiyan Bhandari

Abhiyan is the Co-Founder and Radiology & Imaging Lead of Ophtnotes. He is a doctor who graduated from UCL Medical School in London. He scored in the top 10% of candidates who sat the Duke Elder examination and runs ophthalmology and Duke Elder revision sessions aimed at medical students. He also runs a YouTube channel aimed at medical students, covering topics ranging from study tips, productivity and vlogs of his journey through medical school.

Published: 27/2/22

Last updated: 28/1/25