I'm sorry to hear this and I hope you'll be able to find out what's causing this. The picture that you posted of losing the fur above the eye reminds me of Storm. If he eats cat food that has a lot of fish in it then he'll loose the fur on his ears and above his eyes. He starts scratching like crazy so I really have to watch what I feed him. He's currently on a grain free diet and it does have some fish in it but he also eats a turkey based wet food. So far he's doing well.

Have you changed their diet in any way? Food allergies would be my first guess.