Q: Why I cannot see mid-range with progressive lenses?
A: Progressive lenses are intended around a corridor of optimum vision. An optician must measure carefully and indicate where this corridor—as manufactured within the lenses—has to turn out, depending on where up your eyes is going to be positioned after you examine the lenses placed in your selected frames.
Although "short corridor" lenses might be suited to smaller plus much more fashionable frames, they do not work well in larger frames. Progressive lens designs for larger frames aren't adaptable to smaller ones. It is very of importance to your optician and optical lab to complement the proper lens design on your chosen frame.
Progressive lenses can be purchased in custom configurations. In case you read a whole lot at different close ranges, you might like to have your optician specify a lens design that broadens the size and style and choice of the lens for reading. Special progressive lenses that enhance mid-range vision, e.g., could possibly be preferred by people who spend considerable time when in front of your personal computer monitor.