The Arnam appear to have pure black eyes, which can be very uncomfortable for people to look at. But Arnam eyes are far more sensitive to light than normal human eyes. They can see at light levels we would consider pitch black, whether deep underground or underwater. They have multiple eyelids that they close over those sensitive eyes as they enter brighter environments. At standard light levels for most of humanity, they have closed so many eyelids to filter out the bright light that their eyes appear pure black. Because of the physiological impact those eyes make on most humans, most Arnam wear sunglasses when dealing with other humans. At least that is the excuse they use. I think they just like to wear shades because they look fancy. There certainly is a lot of business when it comes to Arnam-targeted shades, at least, and many of them are…exotic.