What is the central retinal artery?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: October 20, 2026 • View editorial policy

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.

Ask Question

What is the Central Retinal Artery (CRA)?

The central retinal artery is the primary blood vessel supplying the inner retina, originating from the ophthalmic artery (which itself branches from the internal carotid artery), and penetrating the optic nerve approximately 10-19mm behind the eyeball to reach the retina through its center. 1

Anatomical Structure and Course

The CRA has a distinctive anatomical pathway that is critical for understanding its clinical significance:

Origin and Branching

  • Originates from the ophthalmic artery in approximately 93% of cases, typically on the inferomedial side about 8.4mm distal to the orbital end of the optic canal 2
  • In rare cases (approximately 7%), it arises in common with a posterior ciliary artery or muscular branch 2, 3

Course Through the Orbit

  • Follows a sinuous path within the orbital cavity with multiple curves before reaching the optic nerve 4
  • Penetrates the dural sheath of the optic nerve at the junction of the middle and anterior thirds of the intraorbital optic nerve, approximately 18.6mm distal to the optic canal 2
  • In over 70% of cases, enters through the lower medial surface of the optic sheath; 21% enter the inferomedial surface, and 7% the inferolateral or lateral surface 2, 3

Terminal Distribution

  • Travels through the center of the optic nerve to reach the eyeball 3
  • Supplies the inner retinal layers: retinal nerve fiber layer, ganglion cell layer, and inner plexiform layer 1

Functional Significance

The CRA is the sole arterial supply to the inner retina, making it a critical end-artery with no effective collateral circulation in most individuals 1. This anatomical arrangement explains why occlusion leads to devastating visual consequences.

Important Anatomical Variant

In approximately one-third of eyes, a cilioretinal artery is present, which originates from the posterior ciliary circulation (not the CRA) and often supplies the fovea 1. When present, this variant can preserve central vision even when the CRA is occluded, though peripheral vision remains severely impaired.

Clinical Relevance

Understanding CRA anatomy is essential because:

  • Occlusion causes retinal stroke: Central retinal artery occlusion (CRAO) represents an acute ischemic stroke of the eye, with incidence of approximately 1.9 per 100,000 person-years 1
  • Surgical risk: The small diameter and specific course make the CRA vulnerable to damage during orbital surgery, particularly procedures involving the lower half of the proximal two-thirds of the optic sheath 2, 3
  • Time-critical ischemia: Retinal ganglion cells may tolerate occlusion for 97-240 minutes before irreversible damage occurs, though this window varies 1

The CRA's anatomy directly determines the clinical presentation of CRAO: sudden, painless monocular vision loss with the classic funduscopic finding of retinal whitening and a cherry-red spot at the fovea (where the choroid remains visible through the thin, nerve fiber layer-free foveal center) 5.

References

3
Research

The morphometric analysis of the central retinal artery.

Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists), 2005

Related Questions

Where is the central retinal artery (CRA) seen with a fundoscope?
What symptoms are associated with an ocular stroke (central retinal artery occlusion or ischemic optic neuropathy)?
A 10‑day postpartum woman presents with dysuria and a urine culture growing mixed microbiota >100,000 CFU/mL; how should this be managed?
In a 10‑month‑old infant with a slightly indented coronal suture, normal fontanelles, and appropriate head growth, what is the appropriate next step in management?
What is the appropriate 10‑day antibiotic regimen for a patient undergoing ENT follow‑up after image‑guided fine‑needle aspiration/biopsy, assuming no documented β‑lactam allergy?
What are the differential diagnoses for left-sided neck, arm, and chest pain accompanied by left eyelid drooping on awakening?
What is posterior fossa crowding?
How should I evaluate and manage a patient presenting with burning feet syndrome?
How can anaphylaxis be distinguished from hereditary angioedema (HAE)?
How many hours or days does the slow progression phase of hereditary angioedema typically last?
How should acute calculous cholecystitis be managed compared to chronic calculous cholecystitis?

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.