I've had a problem since I had cataract surgery. Reading glasses just don't quite cut it. I found these on Amazon.com and on JoAnn.com and keep at least two in my sewing kit and 2 with each of my machines. They work great on machine and larger eyed hand needles.
http://www.amazon.com/Dritz-Looped-N...edle+threaders
http://www.joann.com/dritz-looped-ne...g/5579099.html
Also, Nova Montgomery sells a needle threader on her website.