Of the five senses humans have, the sense of sight/vision is perhaps the most important as anything that affects it will have a limiting effect on how we function. The human eye is a complex organ, consisting of a number of highly complex parts working together to feed impulses to the brain to enable us to ‘see’:


1. The Sclera – this is the tough supporting wall of the eye

2. The Cornea – the transparent section of the front of the eye, it allows light through into the eyeball, refracting the light inwards.

3. The Pupil – a small hole which allows the light passing through the Cornea to enter the eye.

4. The Iris – a muscle controlled structure which controls the size of the Pupil and therefore the amount of light entering the eye.

5. The Lens – focuses the light onto the Retina at the back of the eyeball.

6. The Retina – the ‘screen’ that the light forming the image eventually projects onto. It contains light and colour sensitive components called Rods and Cones. 

7. The Ciliary Muscles and 


8.Suspensory Ligaments – these work together to control the shape of the lens

9. The Optic Nerve – this highly complex network sends impulses to the Brain from the sensors on the Retina.


The function of the eye relies on the ingress of light, however too much light can damage the retina. The retina is highly sensitive and can easily be damaged temporarily or permanently. This is why we should never look directly at the Sun or similar extremely bright objects.



The amount of light entering the eye is regulated automatically by the “reflex arc” which causes the muscles controlling the Iris to contract, to either widen the pupil (radial muscles) or constrict the pupil (circular muscles).