On their eyes? Weird. I wouldn't call the vet. Not just yet anyways. That could be a big bill for a relatively minor issue. Every mite I have ever learned about can be killed with 7 dust powder, DE, and all other sorts of things that you can buy at the feed store. My personal favorite is permethrin spray. It's much easier to apply, and much faster working than powders in my experience. I recently got 9 meat birds for free who were horribly, horribly infested with mites. They are almost completely naked from their "waist" down. I've bathed them twice and spray them every day. (Every other day right now, because we got pour on permethrin and it's a stronger solution, but it turns thick and milky after a bit of being in the spray bottle which makes it hard to apply, so I don't recommend it.) You don't have to bathe them. I chose to because they were so horribly infested and bathing gets rid of them quicker.
I would get the mite spray (r dust if you would prefer) and put it all over them. Even on the face, but not in their eyes (obviously) or around their nostrils. You may want to rinse their eyes will saline solution every day, until the mites are gone. I think the average life cycle of most mites is about 2 weeks, so I would treat for at least 3, maybe even 4. Separate the 2 that have the mites and check the others. If they have them as well (which they probably do) treat them. Keep the coop clean. You can put DE in the nesting boxes to help prevent mite infestations. You may want to treat the nesting boxes with the medicate spray/powder while you are spraying the chickens as well.
