Mike,
I assume you're talking about an adjustable iris that fits on your glasses? I've never heard it called an "occluder."
Brownells sells the Merit Optical Attachment (there doesn't seem to be a technical term for it). I bought one a few years ago that had a little alligator clip on it to attach to the eyeglass frame. Seems the Merit now attaches to the lens with a suction cup.
Anyway, Google is your friend, and these people sell the newer Merit as well as another manufacturer's flip-up style....
http://64.233.167.104/search?q=cache:zVf...;cd=3&gl=us