What happens to light after it strikes the retina?

Retina is made up of light sensitive cells. Those light sensitive cells are rods and cones. The rods and cons are responsible for vision at low level . they are two types of photo receptor. The rods are more sensitive then cons.     They are responsible for the detection of color and then  change  the  images into signals . The signals start traveling from brain to optic nerve.

i am going to guess that it is co2.