I opted in to my employer's "managed vision care" through Eye-Med this year. I was checking out the various in-network providers, and found that I was better off going to Walmart Optical and getting reimbursed. The frames I wanted were at least $170 at the "preferred providers", leaving me with $50 in out of pocket costs. Walmart had nearly identical frames at $118, just under what I can get reimbursed for.
It turns out that most of the preferred providers (Sears Optical, Target Optical, JC Penny Optical, Pearle, Lenscrafters) are owned by the parent company of Eye-Med. Explains a lot.