New research indicates the ‘whites’ of human eyes are not uniquely human 

Our eyes allow us to communicate with other people without needing to talk, this is in part because of the color variation between our iris and sclera (white part of the eye), explains Kevin Lee.
Lee is an evolutionary anthropology PhD student at the School of Human Evolution and Social Change and is affiliated with the Institute of Human Origins at Arizona State University. Recently Lee, and a team of researchers, published data showing that enough chimpanzees have white sclera making this more than just an anomaly.