The Anatomy of the Eye

The eye is the organ of sight, with specialised structures.

Dot points covered on this page.

2.1 Describe the anatomy and function of the human eye, including the:

  • conjunctiva
  • cornea
  • sclera
  • choroid
  • retina
  • iris
  • lens
  • aqueous and vitreous humor
  • ciliary body
  • optic nerve

Parts of the eye

Conjunctiva

Structure - A delicate membrane that covers the surface of the eye and the inside of the eyelids.

Function - Protects the front part of the eye.

Cornea

Structure - The front part of the eyeball which is transparent and quite thick.

Function - Refracts light rays as they pass through it.

Aqueous Humour

Structure - a jelly like substance that fills the front of the eye.

Function - 1. keeps the eyeball in shape, 2. refracts light towards the retina.

Sclera

Structure - Continuous with the cornea but not transparent, it forms the tough, white outer back part of the eyeball.

Function - Protects the eye and helps maintain eye shape.

Choroid

Structure - The choroid lies on the inside of the sclera. It is a thin black layer which contains many blood vessels.

Function - The pigment absorbs stray light preventing stray images.

Retina

Structure - The innermost layer of the eye. It lines the back of the eyeball with a network of photoreceptors and nerve fibres.

Function - Receives the light images and translates this into electrical impulses which are sent to the brain and deciphered.

Iris

Structure - The coloured part of the front of the eye containing many fibrous muscles.

Function - Regulates the amount of light entering the eye.


Lens

Structure - A transparent biconvex protein disc behind the pupil.

Function - Refracts and bend light rays towards the retina.

Vitreous Humour

Structure - a jelly like substance that fills the back chamber of the eye.

Function - 1. keeps the eyeball in shape, 2. refracts light towards the retina.

Ciliary body

Structure - Connects the choroid with the lens. It contains suspensory ligaments as well as ciliary muscles.

Function - Holds the lens in place as well as altering the shape of the lens depending on the distance of an object. (Accommodation).

Optic Nerve

Structure - Connects the eyeball to the brain. Where the optic nerve connects to the brain is known as the blind spot as no image can be made or processed due to the lack of photoreceptors.

Function - Carries nerve impulses to the visual cortex of the brain so images can be translated.