The color of human eyes is often the same as the iris of the eye, which itself consists of two parts: the anterior layer of iris stroma and the posterior layer or posterior pigment epithelium. Based on experiments, it is believed that iris color is determined based on four factors: pigment granules in the posterior pigment epithelium, pigment concentration in iris stromal melanocytes, melanin pigments in iris melanocytes, and the scattering and absorption of light from the extracellular matrix properties of the stroma. Becomes. In general, melanocytes in the iris stroma have a greater effect on iris color. These types of cells contain a biopolymeric and inert substance called melanin, which itself has two types: brown-black or Eumelanin and red-yellow or Pheomelanin.