If you have trouble seeing the sights, don't move the pistol close to your face, increase your Depth of Field (the distance from your eye where everything is in focus). "But my eyes aren't what they use to be and I can't see the sights clearly. How can I increase my DoF?" Quick, simple, and best of all it's free.
* Take a piece of black electrical tape and a regular paper punch.
* Stamp out some 1/4" diameter circles of tape and stick them to an old matchbook or something similar so that you can remove them easily.
* Then take a small awl or finish nail set and punch a hole in the center and keep it small.
* Now stick one on your shooting glasses where you sight through when shooting like this.
You'll hardly be able to see the black circle as it will appear to be just a ghost image but inside the center you'll notice that you can clearly see both the front and rear sight as well as the target, even if it's 100 yds away!! What you've just done is place a tiny aperture close to your eye. Opticians and photographers understand that to increase your Depth of Field, one needs a tiny aperture to sight through. That's why photographers want to use the smallest aperture setting they can and vary the shutter speed; they get pictures with more of the scene in focus.
Give it a try. It's easy and free.