What is the retinal artery a branch of?

The Retinal Artery is a Branch of the Ophthalmic Artery

The central retinal artery is a branch of the ophthalmic artery, which itself is a branch of the internal carotid artery. 1

Anatomical Pathway

• The ophthalmic artery originates from the internal carotid artery and supplies blood to the eye and surrounding structures 1
• The central retinal artery branches off from the ophthalmic artery and enters the optic nerve approximately 1 cm behind the eyeball 2
• After a sinuous path within the orbital cavity, the central retinal artery penetrates the dura mater covering the optic nerve 2
• The central retinal artery then travels within the optic nerve to supply the inner retina 1

Clinical Significance

• Occlusion of the central retinal artery (CRAO) or its branches (BRAO) represents an ophthalmic emergency that can lead to permanent vision loss 1
• CRAO is considered a stroke equivalent and requires immediate evaluation and management, ideally within 4.5-6 hours of symptom onset 3
• The incidence of CRAO is approximately 1-2 per 100,000 person-years in the United States, increasing with age to about 10 per 100,000 in those over 80 years 1
• Patients with CRAO typically present with sudden, painless decrease in visual acuity and field of vision in one eye 1

Pathophysiology of Occlusions

• Central retinal artery occlusion (CRAO) is a partial or complete obstruction of the central retinal artery 1
• Branch retinal artery occlusion (BRAO) affects any of the branch tributaries of the central retinal artery 1
• Ophthalmic artery occlusion (OAO) is a partial or complete obstruction of the ophthalmic artery 1
• Most non-arteritic retinal artery occlusions are embolic in origin, while arteritic occlusions are commonly associated with giant cell arteritis 1

Risk Factors and Associated Conditions

• Retinal artery occlusions share risk factors with stroke and cardiovascular disease, including hypertension, smoking, hyperlipidemia, diabetes, and atrial fibrillation 1
• CRAO is most strongly associated with ipsilateral internal carotid artery stenosis, with up to 40% of patients having ≥70% carotid stenosis 1
• Patients with CRAO are at high risk for subsequent stroke and require prompt evaluation for embolic sources 4, 3

Management Considerations

• Acute CRAO should be treated as a medical emergency with immediate referral to a stroke center 3
• The therapeutic window for potential benefit appears to be within 4.5-6 hours of symptom onset 3
• Despite extensive research, there are no definitively proven treatments to reverse vision loss from CRAO 3
• Patients require monitoring for development of neovascularization, which may require panretinal photocoagulation if it occurs 1, 3

Understanding the anatomical relationship between the retinal artery and ophthalmic artery is crucial for proper management of occlusive disorders affecting this vascular system and their potentially devastating consequences on vision and overall health.