It doesn't look like an open wound per say.. or puss filled from what I can see.searching for what could possibly be wrong with his eye,
Agree with and appreciate advice from wyorp.
The swelling above the eye.. if just fluid filled should retreat before to long. If it happens to get puss.. it turns thickened in chickens and get's solid filling.. then it *may* need excising.. but NOT now.
So you do have other birds in your flock already??? Is he already friendly with them?
Now that he's acting a bit normal.. watching ins and outs will HELP to rule out internal injury.. (intake & output).

@BigBlueHen53 I can appreciate you line of thinking! I have not had chickens respond to mirrors in the way others do. Your thought about it being seen as competition.. is entirely possible.. though I'm not sure if they can tell that by looking and without sensing the hormones, pheromones, etc that might otherwise be the indicators they use. I don't think a grown boy EVEN a Silkie.. is dumb enough to mistake a stuffed animal for company, but WHAT do I know?!

Yes Silkies are a melanistic breed like Cemani despite not being known quite as well for THAT feature since they do come in other feather color varieties than just black. Just for informational purposes.. or quick easy refresher reference..
Cemani are also clean legged, straight combed, 4 toed, and hard feathered.
Silkies *should* be feather legged, walnut combed, 5 toed, Silkie feathered.. and can come in bearded and non bearded..
The one being helped in this thread is the later, non bearded.. and does indeed have beautiful dark features as one should.

Looks like he'll make a full recovery.. with or without the eye or use of it! Still cautious.. but very optimistic!
