Http://www.pictures-of-nigeria.com/images/cw65-r9-29.jpg Why Do Black People Have Yellow/red Eyes?

Why do black people have Yellow/red eyes? - http://www.pictures-of-nigeria.com/images/cw65-r9-29.jpg

This does not racist (I'm black), but I always wondered why many blacks (especially in Africa) have red eyes and yellow sclera (the part thats should be white). As such http://www.pictures-of-nigeria.com/images/CW65-r9-29.jpg
I found it very common for Africans red / yellow eyes. I know that no hepatitis or other diseases, as (80% of Africans have the red eyes have seen and lived in Africa, liver) affects only about 3% of Africans. I do not know your level of stress (again, Africans and Africans rich have) no red eyes. I want to know what the black Africans, red eyes, eh?