I just got a diopter stick-on by Lyman (not at home, so can't give the trade name. It's a small black plastic disk which adheres to the inside of my lens, lined up to focus on the sight. It cleared my sight picture considerably, though, beyond 40 yds, the target is still a blur. (I'm very near-sighted.) Stiil, centering on the blur, I can get satisfactory group, often all in the black.
Hoping cataract surgery will go a long way to solving my problem. I don't comptete any longer, but still enjoy shooting.