I had my eyes tested at Asda yesterday - not got the glasses yet, but their prices were too good to resist! I have a strong prescription, and I have 2 pairs - single vision for my 'usual' pair and varifocals for my 'reading' pair which grade from reading prescription to middle-distance - these are called occupational varifocals and are perfect for me as I work with computers all the time. My last glasses cost over £200 per pair - cheap frames, but expensive lenses by the time I'd added thinning and photochromic to my single vision pair, the just the cost of varifocals. And they never qualify for offers because of the extras.
Asda do varifocals, thining, scratch resistance and anti-glare at no extra cost and the only charged extra for me is photochromic lenses. And their '2 for' offer covers different lens options as long as they are for the some customer. So, I can get my 2 pairs with nice designer frames for a total of £140 - £120 of which is covered by the hospital fund I pay into at work! Result.