Structure of the Eye and Retina

Structure of the Eye and Retina

1. Pupil- center of the iris (coloured area) in which light enters through and opening in the centre and is projected on the back of the eye.

   • Lens- focuses the pupil, is adjustable
   • Cornea- focus the pupil, is not adjustable

2. Retina- where the light is projected at the rear surface of the eye. Is lined with visual receptors.

   • Light always strikes the opposing side

3. Fovea- the pit at the back of the eye that is specialised for acute, detailed vision.

   • Almost absent of blood vessels and ganglion cells creating unimpeded vision.

4. Rods- respond to faint light and are not useful in daylight. Bright light bleaches them. Abundant in the periphery of the human retina.

5. Cones- less active in dim light and are essential in colour vision. Abundant in and near the fovea.

   • Red- longwave 700nm
   • Green- medium wave 500nm
   • Blue- shortwave 350nm

6. Ganglion cells- recieves messages from bipolar cells (rods and cones) and the ganglion cells join together (close to the center of the eye) and travel to the brain.

   • Blind spot- the ganglion cells form the optic nerve. The point in which it leaves the eye is a blind spot as there are no receptors.

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