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The Optic Nerve

 

 Structure of the optic nerve head (head on)

Behind the pupil, the lens of the eye is suspended from the ciliary body by fine ligaments. The cornea and lens focus a picture of your surroundings on the retina, which is the light-sensitive layer that coats the inside of the eye. The picture of your surroundings is sent from the retina to the brain by nerve fibres, which derive from nerve cells in the retina. The optic nerve is formed by about one million of these nerve fibres collected together. The optic nerve starts at the back of the eye at the optic nerve head, which is also called the optic disc.

 

 

 

 

 

 Structure of the optic nerve (side on)


 



The nerve fibres leave the eye through pores (holes) in the lamina cribrosa, a sieve-like structure in the optic nerve head. Blood vessels enter and leave the eye through the same structure. The nerve fibres form a rim around the edge of the optic nerve head (neuro-retinal rim), leaving a central indentation without nerve fibres called the optic cup.