I'd offer two options:
1) Get your eyes checked by an optometrist who is known to competitive shooters as one who understands the requirements of formal target shooters, and have a corrective lens made to yet your point of focus somewhere slightly ahead of your front sight. The standard wisdom is for focus exactly ON the front sight with the target blurred, but if your preference is for centre aim this is less than ideal, at least in my opinion. I prefer a lens which puts my relaxed focus at about 1metre ahead of the front sight, then use an iris on the back of that lens to adjust apparent focus such that both sights and the target are more or less crisp. I centre-aim as well, though not with that pistol - I use a Pardini K10 for the past year though I often also practice with my older Baikal 46m. Seeing the sight alignment clearly when aiming against black is difficult, but good focus helps a lot.
2) Consider sub-6 hold instead of centre-aim. Aligning the sights against white is the majority method and it's quite understandable; the black sights don't get lost against the off-white paper. Of course there are lots of other arguments for sub-6, but there's loads of reading online to address those. Tried it, lots, didn't like it, so I aim for centre.