EYE ANATOMY

The eye is structurally complex, durable yet delicate, and sophisticated in function. Eye anatomy is displayed here in a detailed diagram that can be used to better understand information on this site.

You will notice structures discussed elsewhere on this website, such as the cornea, iris, pupil, lens, and retina. You also will recognize others that we have not discussed. It isn't that they are not important. They are. But my goal for this website is to simplify information about glaucoma, not to overwhelm you with so much information about eye anatomy that it makes your head spin.

But I know that some of you are interested and want to delve deeper into information about eye anatomy. The diagram below should help you on your journey. Below the figure, you will find an alphabetically listed glossary of eye anatomy that will explain each term in the figure.





Actually, there is another level of eye anatomy structure at the microscopic level. I present some aspects of it when appropriate on the pages of this website, but a comprehensive examination of it is beyond the scope of glaucoma-eye-info.com.

Glossary of Eye Anatomy Terms

Anterior Chamber of the Eye. A fluid-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium. (Endothelium is a thin layer of flattened cells that lines the inside of blood vessels and some body cavities.)

Anterior Ciliary Artery. There are seven anterior ciliary arteries. Each originates from the ophthalmic artery, which branches from the internal carotid artery. These arteries run along the same route as the extraocular muscles to the front of the eye to form a vascular zone beneath the conjunctiva. They then run through the sclera near the cornea and then form the main arterial circle (circulus arteriosus major) around the iris.

Bundles of Optic Nerve. A collection of about 1.2 million optic nerve fibers at the rear of the eye.

Canal of Schlemm. A circular channel in the the anterior chamber of the eye that collects aqueous humor filtered through the trabecular meshwork and delivers it back to the bloodstream through the anterior ciliary veins.

Central Retinal Artery. A branch of the ophthalmic artery that enters the eye under the optic nerve but within its dural sheath. It sends branches over the internal surface of the vitreous chamber of the eye to supply blood to the retina.

Central Retinal Vein. A short vein that exits the eye through the optic nerve and drains blood from the capillaries of the retina into veins outside the eye.

Choroid. A layer of blood vessels and connective tissue located between the sclera (white of the eye) and retina. It forms part of the uvea and supplies nutrients to the inner parts of the eye.

Ciliary Body. A structure in the anterior chamber of the eye that releases a transparent liquid called the aqueous humor within the eye. It also contains the ciliary muscle. This changes the shape of the lens so that the eyes can focus, a process is called accommodation.

Conjunctiva. A thin membrane that covers the inner surface of the eyelid and the sclera (white part of the eyeball).

Cornea. The transparent front part of the eye that covers the iris, pupil, and anterior chamber. The cornea refracts light, accounting for approximately 70% of the eye's total optical power.

Ora Serrata. The serrated junction between the retina and the ciliary body, marking the transition from the simple non-photosensitive area of the retina to the complex, multi-layered photosensitive region.

Episcleral Artery. One of many small branches of the anterior ciliary arteries that perforate the sclera behind the cornea to supply the iris and ciliary body with blood.

Fovea Centralis. A depression in the center of the macula of the retina. It is the area responsible for the most acute vision or line of sight. Only cones are present in the fovea centralis and blood vessels are absent.

Hyaloid Canal. A passage running from in front of the optic disc to the lens of the eye. During fetal development, it transmits the hyaloid artery.

Iris. The colored portion of the eye that is located between the cornea and lens.

Lateral Rectus Muscle. One of six extraocular muscles that control the movements of the eye. The lateral rectus muscle is responsible for abduction, a function that brings the pupil away from the midline of the body.

Long Posterior Ciliary Artery. Arteries arising, together with the other ciliary arteries, from the ophtalmic artery. There are two in each eye. They penetrate the posterior part of the sclera, laterally to the optic nerve, and traverse along either side of the eyeball, between the sclera and choroid, to the ciliary muscle, where they divide into two branches.

Macula Lutea. A yellow oval spot at the center of the retina or back of the eye. It is responsible for sharp, detailed central vision.

Major Perforating Branch. The point at which the episcleral artery branches from the anterior ciliary artery.

Medial Rectus Muscle The largest of the extraocular muscles. Its function is adduction of the eyeball. Adduction means to bring the pupil closer to the midline of the body.

Optic Disc. The location at the back of the eye where ganglion cell axons exit to form the optic nerve. There are no light sensitive rods or cones to respond to a light stimulus in this area, causing an interruption in the visual field called the blind spot.

Pars Ciliaris Retinae. Epithelium lining the ciliary body. (Epithelium is a tissue composed of cells that line the cavities and surfaces of structures throughout the body.)

Pars Plana. A darkly pigmented posterior zone of the ciliary body continuous with the retina at the ora serrata.

Pars Plicata. The folded part of the ciliary body.

Posterior Chamber of the Eye. A small space directly posterior of the iris but anterior to the lens. It should not be confused with vitreous chamber, which is the large space behind the lens that is filled with vitreous humor.

Pupillary Sphincter Muscle. A muscle in the iris. It encircles the eye and functions to constrict the pupil in bright light or during accommodation.

Retina. A light-sensitive layer of tissue at the back of the inner eye.

Sclera The white outer wall of the eye. It is a tough, fibrous tissue that extends from the cornea to the optic nerve at the back of the eye.

Scleral Spur. The origin of some of the ciliary muscle fibers and the anchor of the trabecular meshwork.

Short Posterior Ciliary Artery. Any of 6-10 arteries arising from the ophthalmic artery or its branches that pass to the posterior part of the eyeball while surrounding the optic nerve, and enter or divide into branches entering the sclera to supply the choroid and the ciliary processes.

Trabecular Meshwork. An area of tissue in the eye located around the base of the cornea, near the ciliary body, and is responsible for draining the aqueous humor from the the anterior chamber of the eye.

Vorticose Vein. A vein formed by branches from the back surface of the eye and the ciliary body. It empties into the ophthalmic veins.

Zonule of Zinn. A network of fibrous strands connecting the ciliary body to the crystalline lens of the eye. It consists of two layers: a thin layer lining the hyaloid fossa, and a thicker layer that is a collection of zonular fibers. Together, they are known as the suspensory ligament of the lens.


I hope that you find this information valuable and that it will serve as a resource on eye anatomy as you explore the pages of this website.

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