Long barrel guns shoot more accurately because there is more distance between the front and rear sight making aiming more accurate.But seeing the sights gets harder with age. There area several different solutions which I have used over the last 20 years.
The first is the least expensive. You go to the drug store and pick out a pair of reading galsses that force your eyes to be sharper at the front sight then at the rear or at the target. Obviously you can not take your gun with you. So to determine the magnification, hold your finger up and extend you arm to full length (as you would when shooting a pistol). Try different magnification reading glasses to get the finger sharper without too much compromise in the distance field of view. You might want to place yourself so that you can see a distant object that is about 50 feet or 25 yds or 50 yds (whatever distance at which you shoot pistol targets). The bias should be towards the finger and not the "target". if you wear glasses the reading glass easily slip over the top of them and if it is only shooting glasses you wear then the reading glasses can take the place of them if the brand you buy is safety rated.
The next approach is the rather expensive devices Olympic shooters wear on their galsses. It is a mini lens system (several powers of that lens is usually in the box) that clips to your glasses, shooting or regular. Pick the lens as in the "reading glasses" above. I find this setuyup most usefull for rifle shooting with open sights. Mine was purchased over 20 years ago and is made by Clearsight (Are they still in business????).
The last choice is the Merit device or the several cheaper alternatives. It is basically a very small hole through which you sight. Its hole is so small that it changes the focus ability of the eye and if your eyes are not too bad give you resonable sharpness of the front and rear sight, and the target, at the expense of brightness. It works very well outdoors and more than good enough in well lite indoor ranges.