foamy eye

The oldest duck in the garden is about 12. I've had him (Donald) for a couple of months I guess and he was passed on with another white drake to me by Gill who lives a few streets away. She named him! He's very big, very arthritic and because he's white I can see that the feathers around his eyes are slightly discoloured. He has a large white patch in the corner of one eye - do ducks have third eyelids? I've no idea at present. My duck management books aren't that detailed. So the book mentions foamy eye which can be brought on by a bump or similar injury and often happen when drakes fight over females. I've tried to buy something to soothe it over the counter in an agricultural merchants but they're not allowed to sell stuff like that any more. Taking him to the vets is out of the question - he'd find it very stressful, and because of the panic about birdflu so would the others in the waiting room. It may mean vet consultation or it may just subside over the weekend on its own. Any advice welcome... and yes I have thought about putting a camomile tea bag (cooled) on it but cathching him is part of the trauma for us both!