what causes heterochromia eyes and
Heterochromia iridium, or segmental heterochromia, is different, it occurs when areas, or segments, of the same eye are different colours. Image courtesy of Wikimedia Commons. What causes heterochromia iridis? The pigment melanin is responsible for the colour - or pigmentation - of our eyes. Heterochromia iridis is caused by too much or too little melanin. This can be due to inherited genes or a problem that occurred when the eyes were being formed.