It sounds to me like a sight picture issue and can be corrected by purchasing custom sights by a manufacturer such as Dawson Precision.
Many will argue you should correct the shooter and I would agree for right or left but when it comes to up or down why not customize the pistol so that the shooter is comfortable using their natural sight picture. Here is a video with Dave Dawson, he is explaining how to install his sights but he gives a lot of information you may find helpful about custom sights. I would recommend you go to a competent gunsmith for the installation.
This is an excerpt directly from Dawson's web sight.
"If you purchase a set of Perfect Impact(R) sights directly from Dawson Precision (DP front and DP rear only), we guarantee that your pistol will zero. If it does not, we will give you a new front sight at the proper height free of charge so that it will. If we do not currently offer the height you need, we will make one for you as long as the requested width is already available for your pistol model."
Best of luck,