Blue eyes are a rare sight in Indonesia, a country where the vast majority of the population has dark hair and dark eyes, but some members of an indigenous tribe have the most stunning blue eyes, because of a rare condition known as Waardenburg Syndrome.

Believed to affect about 1 in 42,000 people, Waardenburg Syndrome is characterized by some degree of hearing loss and pigmentation deficiencies, which can include bright blue eyes (or one blue eye and one black/brown eye). It is caused by mutations in any of several genes that affect the operation of neural crest cells in embryonic development. The visual effect of Waardenburg Syndrome is particularly impressive in ethnic groups where blue eyes are a rarity, as you can see in the photos of members of the Buton tribe taken by Indonesian geologist and amateur photographer Korchnoi Pasaribu.

Photo © Korchnoi Pasaribu

Buton Island, which is located in Indonesia’s Sulawesi region, is home to the indigenous Buton people, some of whom suffer from the Waardenburg Syndrome and have the characteristic electric blue eyes (either one or both).

Korchnoi Pasaribu visited Buton Island last month and took some photos of its natives, focusing on their stunning electric blue eyes. He posted the photos on his Instagram, and they have since gone viral, being picked up by most major news outlets and shared massively on social media.