I used to have perfect eyesight. My eyesight has deteriated with diabetes and horror, age. I used to see perfect circles in dot sights. Now they are little stars. But I can still use express sights most of the time. So far at least. When handgun shooting the close targets are fine. I have a little trouble with the handgun and the 20 or 25 metre target. With the rifle, so far it is fine.

Supposedly per Bob Pretty and the other old Trijicon guys who used to be part of Trijicon in Australia, the triangle dot sights can work better for some people. But no one seems to make them for common sale.