First off, be aware that if you have an aggressive forward stance, you may need to lift your head to make the bifocal-type lenses work with your sight.
I just turned 50. I started using cheap reading glasses about two years ago, and as I'm still in the military, deployed to the middle East last fall. I'm in Air Guard security forces after bouncing around the branches, and a civilian cop. Before the deployment, I figured I'd better get in to see an actual eye doctor. I can't recall my close score, but far I'm still 20/15. A civilian doctor gave me a prescription for no-line bifocals. They work well. The Guard issued me regular bifocals (with the line) in several versions-- regular glasses, gas mask inserts, and an insert that can be put into a special nose piece to be used in conjunction with the issued ESS eye protection.
I liked the no-line a lot better. I found on-line a place that will create no-line inserts for the ESS. It was at my own expense, (I think over $300, which I wrote off) but well worth it. I sent them a copy of my prescription. I think the place was called Mountain Optics. If there is interest I'll dig up contact info.