The Eye


  • roughly spherical in shape and with a diameter of 23 mm
  • contained at the back by the Sclera and at the front by the Cornea


  • composed of clear tough fibrous tissue
  • no blood vessels
  • allows light into the eye

Aqueous Fluid

  • clear fluid manufactured and circulated within the front of the eye which escapes by the Canal of Schlemm and is finally absorbed into the blood stream
  • provides nutrition to the front of the eye
  • together with the Vitreous, it is the means of maintaining the pressure within the eye


  • coloured part of the eye which can be seen through the Cornea
  • has a central hole called the pupil
  • by means of two muscles, the iris can rapidly alter the size of the pupil depending on the amount of light available


  • alters shape to focus the image on the retina

Vitreous Fluid

  • clear liquid towards the back of the eye through which light passes


  • delicately thin membrane covering the back part of the inside of the eyeball
  • contains light sensitive cells – cones (responsible for fine discrimination and colour vision) and rods (responsible for peripheral vision and vision in dim light)


  • area of 1-3 mm in diameter
  • area of the retina where cone cells are most abundant and therefore responsible for fine discrimination


  • situated at the centre of the Macula
  • responsible for the finest of fine discrimination

Optic Nerve

  • nerve endings from the Retina join and leave the eye at the point of the Optic Disc (Blind Spot)
  • images are received by the Retina and transmitted to the brain via the Optic Nerve

For more information visit: Vision and Vision Impairment.