Long posterior ciliary arteries

Long Posterior Ciliary Arteries

The long posterior ciliary arteries (LPCAs) are a pair of arteries that play a crucial role in the blood supply to the posterior segment of the eye. They are branches of the ophthalmic artery, which is a branch of the internal carotid artery. The LPCAs are responsible for supplying oxygenated blood to the choroid, ciliary body, and iris.

Anatomy

The LPCAs arise from the ophthalmic artery just before it enters the optic nerve. They travel along the outer surface of the optic nerve and divide into two main branches: the lateral and medial LPCAs. The lateral LPCA supplies the lateral half of the choroid, while the medial LPCA supplies the medial half.

The LPCAs run in a circumferential manner around the optic nerve, forming an arterial circle known as the circle of Zinn-Haller. This circle provides collateral circulation to the posterior segment of the eye, ensuring a constant blood supply even in the presence of occlusion or stenosis of the LPCAs.

Function

The main function of the LPCAs is to supply oxygenated blood to the choroid, ciliary body, and iris. The choroid is a highly vascular layer located between the retina and the sclera. It provides nourishment to the outer layers of the retina, including the photoreceptor cells, and helps maintain the temperature and metabolic balance of the eye.

The ciliary body is a ring-shaped structure located behind the iris. It produces aqueous humor, a clear fluid that fills the anterior chamber of the eye. The LPCAs supply the ciliary body with the necessary nutrients and oxygen for the production of aqueous humor.

The iris is the colored part of the eye that controls the amount of light entering the eye by adjusting the size of the pupil. The LPCAs provide blood supply to the iris, ensuring its proper function and maintaining its health.

Clinical Significance

Any disruption in the blood supply to the posterior segment of the eye can lead to serious visual complications. Occlusion or stenosis of the LPCAs can result in ischemia (lack of blood flow) to the choroid, ciliary body, and iris, leading to various conditions such as choroidal ischemia, ciliary body dysfunction, and iris atrophy.

Choroidal ischemia can cause vision loss, as the choroid is responsible for supplying oxygen and nutrients to the outer layers of the retina. Ciliary body dysfunction can result in decreased production of aqueous humor, leading to increased intraocular pressure and the development of glaucoma. Iris atrophy can cause irregularities in the shape and function of the pupil, affecting the visual acuity and light sensitivity of the eye.

Conclusion

The long posterior ciliary arteries are essential for maintaining the blood supply to the posterior segment of the eye. They play a crucial role in supplying oxygen and nutrients to the choroid, ciliary body, and iris. Any disruption in their blood flow can lead to serious visual complications. Understanding the anatomy and function of the LPCAs is important for diagnosing and managing various eye conditions related to their dysfunction.

References

1. Cassin, B., & Solomon, S. (1990). Dictionary of Eye Terminology. Gainesville, FL: Triad Publishing Company.

2. Kanski, J. J., Bowling, B., & Nischal, K. K. (2011). Clinical Ophthalmology: A Systematic Approach. Edinburgh: Elsevier/Saunders.

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