Avatars from all nations have their eyes glowing when entering the avatar states. No nation, beside the air nomads, has any extra special visual effect.
Why do the tattoos glow? I know the tattoos are very spiritual and an air nomad will get his/her tattoos only when they master airbending, but it is still only cosmetics.
We can assume that The Legend Of Korra ended in modern time (according to technology on the show), Will any avatar that gets a tattoo should have it glowing while in the avatar state?