I have a Leupold 45x 1 inch tube Will there be any improvement if I replace it with a Sightron 10x50 30mm tube Another thought is there an eyeglass prescription I can tell my optometrist that will improve my "scope vision"
Where to begin?
First off, the Leupold you have is a 45X45 fixed power. I had to go to the Leupold site to dig up the name. It has a 45mm objective lens, 38MOA of adjustment range and an exit pupil diameter of 1mm (45/45), which means you have to be positioned very properly behind it to get the full picture and it's probably darkish on overcast days or early morning, late afternoon settings.
Second, you did not say which Sightron you are considering. Since there is no 10X50 model, I figured you probably meant 10-50X something model. There is indeed an SVSSED 10-50X60. It has a 60mm objective lens and 70MOA of adjustment range but it has a 34mm tube and you said the one you're looking at has a 30mm tube. So I went looking for other ones and found a SIIISS 10-50X60 scope with a 30mm tube. It has a 60mm objective and 50MOA of elevation thanks to its larger 30mm tube. If you set it at 45X to match the Leupold, the exit pupil of the Sightron will be 1.33 mm compared to the 1mm of the Leupold, which (if I calculated correctly) is about twice as big in area.
So, in theory and at the same magnification, the Sightron will be easier and somewhat brighter to look through compared to the Leupold because it has a larger objective lens (60mm Vs 45mm) and it has nothing to do with the size of the main tube since the inner tube is probably about the same ID. Of course, the Sightron will have more lenses and if not properly coated that may reduce the amount of light transmission but that's probably nothing to worry about.
Talk to your optometrist and tell him/her about using a riflescope. I have bifocals which means that the top half of my glasses are corrected for my distance vision. Looking through a scope, you are actually focusing on the near image transmitted by the ocular lens and of course, when you're on the ground, you're actually looking through the top of your lenses, which is not the best. My distance vision correction is minuscule, but thanks to age, my near vision has been deteriorating. So, you can adjust the diopter setting on the ocular of the riflescope to make sure you adjust the image of the reticle to be compatible with whatever vision correction you decide to use.