I've got the same limitation...
Basically,the FAA doesn't allow for contact lenses that correct for near vision. However, some of us have very, very poor distant vision. In fact, our lack of distant vision is so bad that it affects our vision in the two foot range. And that affects our "near vision."
So really, when I have my contacts in, I can test at 20/15 anywhere, anytime. Without them, I can test at like 20/a million distant, 20/30 or so near vision. But they realize that most of us wear those contacts all the time--and thus have no practical need for near vision help.
But, the rules say we "need" it. So, they say that we must possess GLASSES that correct for near vision. Nowhere does it require me to actually use them. In fact, I carry a kneeboard because it contains two things: a pack of gum, and my glasses. The gum I use, the glasses I have NEVER used. I actually took the price tag off of them when I took my CFI checkride a few years ago--just in case.
I'm guessing that is why you have the limitation as well. Me, I wear my contacts full time, and carry a pair of reading glasses everywhere I fly--even if I have no need for them. Of course, if I were to wear a normal pair of glasses, I wouldn't need to carry the reading glasses around. I've never seen an FAA document classifying certain pairs of glasses as near or distant vision--if you can pass the near and far vision tests with one pair of glasses, then wair that one pair. But if you use contacts, carry a pair of reading glasses.
There's how I see it, based on my questions to a few AME's about that restriction. Hope that helps.
Dan