Wednesday, April 8, 2015

Why do our eyes get black if we enter a room from outside?

Suppose , we spent most of the time in a bright sunlight ; suddenly wish to go back to our room to take rest , as we enter the room from outside , we feel our eyes got black i.e. we can not see anything correctly for a few moments.

Why does it happen ?

It is all because of pupil of eye . Pupil is that part of eye , which is round and black in colour and easily visible when we look at the eyes of another person.

It contracts and expands depending on the amount of light . Thus it can block the amount of light entering the eye in bright conditions.

When we are out in the Sun , pupil becomes tiny and it is allowing very little light to enter the eye. But when we go into a dark room , there is not enough light to pass through narrow passage of pupil . That means now pupil must enlarge itself to get a clear image of things in available little light .

This transformation of pupil takes little time , hence we feel that our eyes are getting blackened. But as pupil adjusts itself , we will get clear image.