The Duhma were a rare sentient species that was divided into many tribes. The tribes identified themselves through use of ceremonial tattoos. The Duhma lived on the dark side of their planet and had lost their sight over time. As a result, they wore dark visors during their occasional journeys off their planet to protect their highly sensitive eyes.
Abal Karda used a visor and Duhma tattoos as a disguise after he was marked as an Enemy of the Empire.