Yes, they accept the VSP. You can use the VSP to buy the pair of eyeglasses. Since the walgreens open this service, they receive more and more guests. And people tend to buy eyeglasses there because the suitable price, good service and good quality. The most important thing is that the buyers can use the VSP.
I don't know if walgreens takes VSP since i never concern this issue when i buy Over counter reading glasses there. But if you want to save money, walgreens is a good place to go because they provide FSA plan when you buy eyeglasses there. Walgreens has a special section on their websites designed for FAS. You can have a try.
I searched the internet and find no clear answer for VSP in Walgreens. Walgreens official website dose demonstrated that they accept many kinds of insurance but VSP is not mentioned. You can contact them for an acute answer. They give out the mail address, phone number and address on their homepage. Turn to them for a sure answer.