Actually Walmart are not contracted with VSP but they do accept assignment. For routine vision exams, Walmart will bill VSP for the non-contract rate and then the member pays the balance between the non-contracted rate and the amount Walmart billed.
I am afraid not. Walmrt is a retail store. While VSP usually cover independant Dr's not the "retail" optometrist. So it may not cover walmart. However, you'd better contact the provider through VSP, or go to their website to get more information about the coverage. Even if walmart don't accept VSP, you can afford to get glasses frames there because eyeglasses at walmart are usually cheap.
Usually, VSP will not deal with a large number of 'retail' optometrist, but some independent Dr's. You shall know that VSP is a PPO network. You can visit Walmart, but you will only get reimbursed. That is to say, You need play for the eyeglasses if you want to get it from Walmart. Go to http://www.VSP.com to look for a Dr on your local network if you want to use VSP. Hope this work.