The names describe roughly their shape but they have different functions. The Rod cells, of which we have about 120 million are more numerous towards the outer edge of the Retina and their task is to pick up movement at the edge of the normal field of vision and also to respond to low levels of light. They help us see at dusk. There are far less cone cells, about 6 million in a normal eye and these are concentrated around the centre of the retina. Their task is to respond to details such as reading and also to respond to colour.
<< Back to Previous Page