Hands up if you have bifocals, or varifocals... well, this post is for you. I didn't find out about this stuff until i'd bought my new lens following surgery, BUT next time I get new glasses, varifocals are old hat history; too limiting by far. Have a look at Waveform and Freeform lenses (aka digital lenses). They work out about 30% more expensive, BUT, the focus gradient corridor is MUCH wider !!!
Thought i'd share, just in case any of you are due a new pair. :)