I can’t find the study I’m looking for, you benefit from my reject pile. Third one for today is pretty big.
“VA is better when one of the focal lines lie on the retina irrespective of the axis orientation; accommodation favors this situation.”
This flies in the face of the “Circle of Least Confusion” method of choosing cylinder correction. I think what they’re saying about accomodation is that if one axis is clear and you can engage the ciliary muscle to make the other axis clear, that gives the visual cortex the maximum amount of image data to process.
If your astigmatism is true cylinder astigmatism, the “Circle of Least Confusion” correction might work well for you, but if your eye is a bit irregular, like most people, using accomodation to see the image at multiple focal lengths may provide overall better visual acuity.
This may also be why staring at something causes it to clear up. Your visual cortex and your ciliary muscles have time to play around and find all the image components necessary to form a full clear image. I might even dare say “clear flashes” are explained here.