Thought I would ask here since many of the 50+ members probably are wearing bi or tri focal glasses. I know that there is a thread on bike mirrors, but it didn't have what I was looking for.

I have always had a mirror on my bikes since getting back into cycling. When I bought my Defy I tried using a mirror that attaches to your eyeglasses. For whatever reason, I couldn't get used to them so I bought a mirror that mounts on Shimano STI shifters (Sora/Tiagra w/gear indicator) and gets attached under the hood. My new bike has Ultegra shifters and the mirrors don't fit without cutting a section of the hood. That's not happening!

Today, I bought a Third Eye helmet mount mirror and was wondering how easy is it to get used to if you wear prescription bifocal glasses when you ride? I haven't mounted the mirror yet and probably won't do so until Friday. I haven't been using a mirror on my daily MUP rides, but I did a club ride this past Saturday without a mirror and I was really uncomfortable riding on busy city streets without one. I have a charity ride on Saturday and would really like to have a mirror to see what's behind me as this ride is on a busy street that goes along the Gulf beaches. Thanks in advanced for any and all opinions and comments.