The Eye​

 

The human eye has a very thin transparent layer. It is called Cornea​

 

It is through this panel that light enters the eye. Maximum refraction of light entering the eye occurs through this transparent membrane.​

 

Behind this cornea is a dark fleshy membrane. It is called iris. Different people have different iris colors.​

 

In the center of the iris is a small opening of variable diameter called the pupil.​

 

If the light falling on the eye is too bright, pupil contracts while if the light is dim, it widens. On the surface of the iris, there is bulge of transparent layers. ​

 

There is a double convex transparent crystalline lens, just behind the pupil. The lens provides small adjustments of the focal length to focus the image. This lens creates real and inverted image of an object on the screen inside the eye.​

 

This screen is made of light sensitive cells and is called the retina. These cells get excited when light falls on them and generate electric signals. ​

 

These signals are conveyed to the brain through optic nerve​