It's hard to say with just a picture. It could be a cyst (dogs often get meibomian cysts, but I've never seen a rabbit with one). Or it could be rabbit syphilis. I'm more used to seeing the growths from syphilis around the nose and mouth, but I have occasionally seen them by the eyes too (although those rabbits had growths in the other more typical locations too). If it is a cyst, then there's not really anything to be done about it. If it's syphilis, a round of antibiotics or two will take care of it.