I'm beginning to think this. I have varifocals and wonder how online companies get the 'sweet spot' right, and adjust the lens accordingly.Not necessarily the cheapest but the best for quality and service is a good independent optician, especially if, like me, you take a varifocal that requires careful measurement and proportioning of the zones. I simply would not trust an online seller to get this right especially as my local guy takes a good ten minutes just measuring, checking and considering. As a regular customer I get top service such as a free repair recently when the bridge of my frameless specs snapped. He also has a rare retinal MRI scanner, which he uses for patients sent to him by the NHS and he doesn't charge me the £50 fee for doing an eye health-check you won't get at many other opticians.
I might go for some online sunglasses that only get used for distance rather than close up/reading.