The Anatomy of the Human Eye

Despite its complex structure, the anatomy of the eye is considered a fairly well-understood part of the human body. However, new knowledge is still being unearthed as research continues. Here is an overview of the different parts of the eye. In this article, we’ll explore the Retina, Ciliary body, and Choroid.

Ciliary Body

The ciliary body is a 5 to 6-mm ring of tissue situated behind the iris. The ciliary body contains a ciliary muscle and the tissue secreting aqueous humor. It also contains the zonular fibers that attach to the peripheral portion of the crystalline lens and keep it in place. This page.

The ciliary body is divided into three parts – the outer longitudinal portion attaches to the scleral spur, the middle oblique portion to the trabecular meshwork fibers, and the inner circular portion attaches to the lens. When the ciliary muscle contracts, it reduces zonular tension on the crystalline lens, allowing it to move forward and assume a more spherical shape.


The choroid of the human eye is a highly vascularized tissue that lies between the retina and the sclera. It plays a key role in the metabolism of the eye. It can be thin or thick, and secretes growth factors, making it an important organ for ocular development. The choroid may also change position during growth and support emmetropisation, although its exact function is unclear.

Previous reports of the choroid of the human eye found a significant relationship between ChT and refractive error (Rx) and axial length (AT). Hyperopic eyes had a thicker choroid, while myopic subjects had a shorter axial length.


The human retina lines the inside of the eye and surrounds the vitreous cavity. It develops from the optic cup (invagination of the embryonic forebrain). The inner wall becomes the neural retina, while the outer wall forms the retinal pigment epithelium. The retina is protected by the sclera and held in place by the cornea.

The retina is composed of thousands of tiny, cellular rods and cones that convert light into electrical impulses. This layer sends the information from the visual field to the brain. It is separated into external and internal layers, with three cranial nerves connecting the retina and the eye muscles.

Optic Nerve

The optic nerve is the portion of the human eye that transmits visual information from the retina to the brain. It is part of the central nervous system (CNS) and is surrounded by the brain’s meningeal layers, as well as cerebrospinal fluid. The nerve is divided into four parts: the head, the optic disc, the intraocular part, and the retina.

The optic nerve is made up of a complex network of axons and glia. It contains between 770,000 and 1.7 million nerve fibers. These fibers connect to a small number of photoreceptor cells in the fovea and to thousands of photoreceptor cells in other parts of the retina. Damage to the nerve can result in severe or permanent vision loss. Damage to the optic nerve should be diagnosed by testing the pupillary reflex.


The sclera of the human eye is composed of white, fibrous tissue that supports the eyeball and provides structure. It is continuous with a clear cornea and covered by the conjunctiva, which is a transparent mucus membrane that lubricates the eye. The thickest part of the sclera is located near the optic nerve. It is made up of two layers: episclera, which is the white outer layer, and lumina fusca, which is made up of elastic fibers. See it here.

The white sclera is important for gaze discrimination. It provides robustness against noise from surrounding environments. The white color of the sclera may also indicate physical health. For example, certain diseases, such as hepatitis, can discolor the sclera to a yellow color.