Seeing At Night

We are aware of some things about our eyes. Our eyes need light to see. Have you ever thought how our eyes see in the dark? This is possible because of some parts of our eyes are working together especially three parts of the eyes that work wonders in varying light conditions.

The pupil

Our eye is like a camera. In a camera, there is aperture which allows light to pass through to let less or more light according to the condition by expanding and contracting. In the similar way the pupil in our eyes works. It shrinks smaller in size when there is bright light to reduce or block the amount of light reaching our retina. In the same way it becomes bigger when there is darkness. One can flash a light in someone’s eyes to see the pupil expanding but be sure that you warn them first.

Rod and cone cells

There are two different types of cells known as rods and cones in our eyes. Fine details and colors are perceived by the cone cells and in order to do so they need bright light. On the other hand rod cells can only see black and white. Their resolution is very poor but is very sensitive even when there is very low light. The white seen by cones are 1000 times increased in brightness to be picked up by the cone cells.

Photo pigments

They are chemicals present in rod and cone cells and are light sensitive. They are the ones which convert light energy to electrical energy and send it to our brain. The photo pigment named ‘Rhodopsin’ is responsible for night vision. Intense light decomposes the pigment, finally reducing sensitivity. Dark adaptation is a process in which the molecules are regenerated during darkness to make our eyes see in low light conditions.