Light penetrates to the third layer. This layer contains cells known as rods, which are sensitive to brightness, and cones, which are responsive to light of different wavelengths corresponding to the colors red, green, and blue.
Gaisma iespiežas līdz pat trešajam slānim, kurā atrodas šūnas, ko sauc par nūjiņām un vālītēm: nūjiņas ir jutīgas pret gaismas spilgtumu, bet vālītes uztver dažāda garuma viļņus, kuriem atbilst sarkanā, zaļā un zilā krāsa.