From what you said, I can see that you are interested in their difference in sensitivity to sun light. And it is true that their difference indeed exists. The causes of that phenomenon is quite complicated which has got something to do with races and geographical distribution. Because people near the tropical areas constantly expose their eyes to sunshine, thus, their eye color would be dark brown and not that sensitive to sunshine, on the other hand, people near some cold areas tend to have light eye colors due to a lack of sunshine.
It is reasonable that the light colored eyes are more sensitive to the sunlight because of the principles of optics. As we know, the dark color will absorb the sunlight. Thus, the light colored eyes will be more sensitive to the sunlight. However, there are many reasons causing the difference of the sensitive degree of the eyes to lights, like the pupil size, the iris problem and so on. Eyes is a can sense light organ. The most simple eyes structure can detect surrounding environment of light and shade. More complex eyes structure can provide visual compound eye usually in arthropod which found that it often have a lot of simple small eye surface composition. It can produce an image in many vertebrates and some software animals. The eyes through the light projection light are sensitive to retinal imaging. The light is accepted and translated into a signal which travels through the optic nerve to the brain. Usually the eyes are spherical, full of transparent gelatinous material. It can control the amount of the lights coming into.