I use a Merit optical attachment to my shooting glasses
http://www.meritcorporation.com/products.html
Works like a camera diaphragm to extend your depth of view.
I am long sighted and can clearly see target but sights are a problem if I wear glasses to see front sight, I cannot see target at all.
With the Merit I can see both - even with a Luger (yes the sights are a challenge).
But ignore the attach with a suction cup - it will fall off.
I played using the suction and then glued it when I found the correct placement where it has sat for years now (I can dimly remember 60)