[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Ophthalmology](https://durgical.com/en/ophthalmology/) › [Clinical anatomy and physiology](https://durgical.com/en/ophthalmology/areas/anatomy-physiology/) › The uvea: iris, ciliary body and choroid # The uvea: iris, ciliary body and choroid - Anatomy and physiology The uvea is the eye's vascular middle layer: the iris sets the pupil, the ciliary body focuses and makes aqueous, and the choroid feeds the outer retina. Updated Nov 5, 2026 **See it in 3D:** [Iris](https://durgical.com/en/anatomy/iris/) · [Ciliary body](https://durgical.com/en/anatomy/ciliary-body/) · [Choroid](https://durgical.com/en/anatomy/choroid/) ## Key points - Iris, ciliary body, choroid = uvea. - Sphincter: parasympathetic (III); dilator: sympathetic. - Anterior uveitis: HLA-B27; posterior: toxoplasmosis. - Uveal melanoma: commonest primary intraocular cancer of adults. ## What it is The uvea is the pigmented, vascular middle coat of the eye, between the sclera and the retina. It has three parts that work very differently: the iris controls how much light enters, the ciliary body focuses the lens and makes aqueous humour, and the choroid supplies the outer retina with one of the highest blood flows in the body. Inflammation of any part is uveitis, named by where it is. ## Clinical anatomy - Iris: a pigmented diaphragm with a sphincter muscle (parasympathetic, oculomotor nerve via the ciliary ganglion) and a dilator muscle (sympathetic). - Ciliary body: ciliary muscle (accommodation) and ciliary processes, whose epithelium secretes aqueous humour and anchors the zonules. - Choroid: a dense capillary bed between the sclera and the retinal pigment epithelium. - Blood supply from the long and short posterior ciliary arteries and the anterior ciliary arteries. ## Physiology - The pupil narrows in bright light and for near vision, and widens in the dark and with sympathetic activity. - Contraction of the ciliary muscle relaxes the zonules so the lens rounds up for near vision. - The choroid nourishes the photoreceptors and helps remove heat from the retina. ## Clinical correlation - Uveitis is classified by site: anterior (iritis), intermediate, posterior and panuveitis. - Acute anterior uveitis is often linked to HLA-B27 and spondyloarthritis; in children, juvenile idiopathic arthritis causes silent anterior uveitis. - Posterior uveitis in Colombia is often due to toxoplasmosis. - Uveal melanoma, usually in the choroid, is the commonest primary intraocular cancer in adults. ## Next step / Initial management - Painful red eye with photophobia and a small pupil: same-day ophthalmology for anterior uveitis. - Recurrent or bilateral uveitis: ophthalmology with workup for systemic causes (HLA-B27, syphilis, tuberculosis, sarcoidosis, toxoplasmosis) according to the pattern. - Children with juvenile idiopathic arthritis: regular slit lamp screening, because their uveitis has no symptoms. - Pigmented lesion of the fundus that grows or is raised: ophthalmology to exclude melanoma. ## Test yourself Think of the answer, then tap the question to see it. ## Which nerve supplies the iris sphincter? Parasympathetic fibres of the oculomotor nerve, relayed in the ciliary ganglion. ## Why do children with juvenile idiopathic arthritis need slit lamp screening? Because their anterior uveitis is often painless and white, and can cause blindness unnoticed. ## What is the commonest primary intraocular cancer in adults? Uveal melanoma, usually in the choroid. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/ophthalmology/the-uvea-iris-ciliary-body-and-choroid/) ## Elsewhere in DurgiPedia - [The eye wall: cornea, sclera, uvea and lens](https://durgical.com/en/histology/the-eye-wall-cornea-sclera-uvea-and-lens/) - [The visual pathway, pupillary reflexes and eye movements](https://durgical.com/en/physiology/the-visual-pathway-pupillary-reflexes-and-eye-movements/) ## Connections ## See it in 3D 3 The structures of Durgical's 3D anatomy where it is found. - [Iris](https://durgical.com/en/anatomy/iris/) - [Ciliary body](https://durgical.com/en/anatomy/ciliary-body/) - [Choroid](https://durgical.com/en/anatomy/choroid/) ## Related 5 - [The anterior chamber and the drainage angle](https://durgical.com/en/ophthalmology/the-anterior-chamber-and-the-drainage-angle/) - [The lens and zonules through life](https://durgical.com/en/ophthalmology/the-lens-and-zonules-through-life/) - [Rheumatic and autoimmune disease in the eye](https://durgical.com/en/ophthalmology/rheumatic-and-autoimmune-disease-in-the-eye/) - [Systemic infections in the eye: syphilis, TB, toxoplasma](https://durgical.com/en/ophthalmology/systemic-infections-in-the-eye-syphilis-tb-toxoplasma/) - [Anisocoria: which pupil is abnormal](https://durgical.com/en/ophthalmology/anisocoria-which-pupil-is-abnormal/) ## Related conditions 5 - [Uveitis](https://durgical.com/en/conditions/uveitis/) - [Ocular toxoplasmosis (retinochoroiditis)](https://durgical.com/en/conditions/ocular-toxoplasmosis/) - [Ankylosing spondylitis](https://durgical.com/en/conditions/ankylosing-spondylitis/) - [Juvenile idiopathic arthritis](https://durgical.com/en/conditions/juvenile-idiopathic-arthritis/) - [Sarcoidosis](https://durgical.com/en/conditions/sarcoidosis/) [← All of ophthalmology](https://durgical.com/en/ophthalmology/) Educational content; not a clinical guideline and no substitute for assessment by a health professional. For sudden visual loss, severe eye pain, a chemical burn or an eye injury, go to an emergency department at once. Sources: [Uveitis](https://www.ncbi.nlm.nih.gov/books/NBK540993/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Anatomy, Head and Neck: Eye Iris Sphincter Muscle](https://www.ncbi.nlm.nih.gov/books/NBK532252/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Anatomy, Head and Neck, Eye Ciliary Muscles](https://www.ncbi.nlm.nih.gov/books/NBK482132/) (StatPearls Publishing (NCBI Bookshelf), 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/ophthalmology/the-uvea-iris-ciliary-body-and-choroid/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/ophthalmology/the-uvea-iris-ciliary-body-and-choroid/