I’ve been thinking about astigmatism quite a bit recently. Just trying to build pictures in my head of why it manifests as directional blur, etc. I’ve been meaning to update the page on the wiki at some point, but haven’t got round to it yet.
With reference to the picture on https://wiki.endmyopia.org/wiki/Astigmatism#Understanding_astigmatism and assuming your astigmatism is “regular”
For close enough objects, I’m guessing that the eye uses accommodation to keep the middle of the spread-out focus on the retina, so that some image is focusued in front of the retina, some behind, giving a circular blur.
As the object moves away, accommodation is no longer able to sustain that, and so the whole mess moves forwards, and this is how the directional blur manifests - the axis which focused in front of the lens moves further forward, and so spreads out even more by the time it reaches the retina. The other direction, which was spread out on the retina because it was focused behind it, now focuses closer to the retina and is sharper. I’ll do some sums with your numbers to see if that’s consistent.
So if I’m right, the answer is that you can do either to improve the directional blur… increasing spherical will push back the “circle of least confusion”, allowing you to keep it centred on the retina. Or increasing cylinder will reduce how spread out the focus is, and therefore also improve things.