First...
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In the pic, his eyes look fine to me. HOWEVER, if perchance something has gotten into one, he may be trying to clear/wash it. He'll need water to do that, and IDK if a dripper will supply it where & how he needs it.
I know that when I get something in one of my eyes, I don't move around much either until it's cleared.
If you mist only at lights-on & lights-off, that may not be enough to help him out here. It won't hurt to mist manually a couple/few more times a day just until he can wash his eyes, then go back to your regular schedule.
As far as calling a vet... How long does it take to get an appointment? (You can call & ask). If it's a short time (1-2 days) I'd wait to see if this takes care of itself. If appointments are a week or more off, I'd schedule one, and watch the cham. If things clear up within a day or two, you can call and cancel the vet (but give them 24 hrs courtesy). If the problem persists, you've got the appointment and can take him in. I don't think it'll come to that.