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Anatomy of the eyeball

Learning objectives

After completing this study unit you will be able to: 

  1. Identify the three layers of the eyeball.
  2. Locate the chambers of the eyeball.
  3. Describe the general structure of the lens and ciliary body of the eyeball.

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The globe shaped eyeball sits within the orbit of the skull and contains the optical structures responsible for vision. 

The outer fibrous layer (external tunic) is formed by the sclera, also known as the white of the eye and the protruding translucent cornea. The middle vascular layer (middle tunic), also known as the uvea, consists of three connecting layers: the choroid, ciliary body and iris. The inner layer (internal tunic) is formed solely by the retina

Between the cornea and lens are two chambers (anterior and posterior) which are separated by the iris. The anterior and posterior chambers communicate with each other via the pupil and are filled with a nutrient rich fluid known as aqueous humor. A third, postremal chamber is located posterior to the lens which houses the vitreous body of the eye. 

Find out more about the anatomy of the eyeball by watching the video below.

Now that we have had a look at the anatomical structure of the eyeball, let’s take some time to take a closer look at the lens and ciliary body. The lens is a transparent biconvex structure that focuses and transmits light to the retina while the ciliary body facilitates accommodation (focusing) of the eye and produces aqueous humor. 

Find out more about these structures in the following video.

Take a quiz

That is quite a lot of structures to remember! Try out the quiz below to help consolidate your knowledge.

Test your knowledge with a broader topic focus and take our custom quiz on the anatomy of the orbital region:

Download the following PDF worksheets and learn the different parts of the eyeball.


Browse atlas

Take a closer look at the anatomical structures of the eye in a transverse section of the eyeball below.

Now let’s take a closer look at the lens and ciliary body of the eye through a posterior view of a coronal section of the eye.

Lens and ciliary body (posterior view)


Key points about the anatomy of the eyeball
Connective tissue layer  Anterior: Bulbar conjunctiva
Fascial sheath of eyeball
Fibrous layer 
(External tunic)
Cornea: Bordered by corneoscleral junction
Features venous sinus of sclera, sulcus sclerae, scleral spur
Vascular layer 
(Middle tunic)
Iris: Surrounds pupil, contains sphincter pupillae/dilator pupillae muscles
Ciliary body:
Corona ciliaris/pars plicata (with ciliary processes and folds), orbiculus ciliaris/pars plana, ciliary muscle, zonular fibres
Inner layer 
(Internal tunic)
Retina: Nonvisual retina (iridal and ciliary parts), ora serrata, optic part of retina
Intraocular part of optic nerve:
Optic disc
Chambers  Anterior chamber 
Posterior chamber 
Postremal chamber: Vitreous body (with vitreous humor/membrane, hyaloid canal)
Refractive media Cornea 
Aqueous humor
Vitreous body (and vitreous humor)

Well done!

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Now that you have come to grips with the anatomical structure of the eye, why not begin learning about the surrounding structures of the eye and its associated neurovascular supply.

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