I am due some new specs. and thought of trying the internet,anyone had any dealings online, looking for varifocals. Looking at the sites some seem to give you more for your money. I am not trying to scrimp just trying to get a btter deal.
I've used Glasses Direct for some time and they are good value with good service. I will not include a link as I see there is one below the last thread (on my PC anyway). It is easy with single vision glasses but less so with varifocals, but they have good telephone support.
As stated by wiz-king, you need to get a prescription from a local opticians first for which you may need to pay depending on age or (lack of) medical reasons.
jaraba is right. It is something about needing the pupilliary distance. Opticians should put it on the prescription, but they rarely do. It's their way of of getting to buy in-house.
In my case it was easily resolved by sending an old pair of specs, free of charge, to Glasses Direct and they worked it out from there. If you do not need varifocals, you need not worry about this aspect.