Sudesh:

If the issue is only the point of impact, you could install a taller front sight to move the point of impact lower. There's a formula for how much taller the front sight needs to be, although I cannot remember it. I'm sure someone more mathematically inclined than I will post it in due course.

If the problem is that your eyesight will no longer allow you to use the standard iron sights on your rifle, well, welcome to the club. Getting old is no fun, but it does beat the alternative.

Rem