There is only brown pigment for eye colour. Other eye colours like blue, green, hazel, etc are what people might call is an optical illusion. Pigments in our body are determined by something call melanin.
Dr. Gary Heiting, a licensed optometrist and senior editor of the eye care website, All About Vision, said, "Everyone has melanin in the iris of their eye, and the amount that they have determines their eye colour. There's really only (this) one type of pigment."
Foreign media reported that the pigments in our body are determined by something call melanin. Irises are made up of a miniature version of melanin called melanocytes, which only come in brown colour.
He said in his report that brown-eyed people have more melanin, less than light. Those with less melanocytes can't absorb as much light, so more light is reflected back out of the eye.
This is called scattering - and when light is scattered, it reflects back at shorter wavelengths. On the colour spectrum, shorter light wavelengths correspond with the colour blue.