Most of the time I don't need glasses, but my "Vari-Focal" spectacles are handy for protecting my eyes, and makes all round vision when driving, slightly clearer....
My long range vision is fine, but as I get older my close-up vision (reading, etc) is getting difficult.
During my recent eye test I told the Optician that I was having problems with with my close-up vision from 9 Inches, (book reading), to 2 Feet distance...(the Computer Monitor Screen), so they modified a pair of Vari-Focal Lenses to gradually magnify an area in the centre and bottom of the lenses when looking down at objects, and looking at the Computer screen from a sitting position....
...they work perfectly...!
"Vari-Focal" Lenses provide a gradual transition in clarity depending what part of the lens you look through...
Bi-Focals only provide two areas..long range, and short range.
I think Folks who regularly suffer from "Migraine" will suffer from headaches for whatever reason...they are generally stuck with it!...
Paul...a Pint Glass for me...please...

...!