How bad does your astigmatism have to be? I've only ever been able to get one magic eye poster to work for me in my life, and I had no idea astigmatism had any impact until just now! I don't know if mine counts as severe, but this would explain a lot for me.
As it happens, I also can't focus on the images in TFA after crossing my eyes to get the shimmer the author refers to.
My daughter has a mild astigmatism (enough to where she needs to wear contacts) and can do the magic eyes very quickly… but maybe that’s only when she’s wearing contacts
I don’t know for sure, but it would make sense if it had to be fairly severe. If it were not enough to meaningfully distort one eye vs the other it would not seem to be detrimental. It’s only when the two images can’t be correlated any more that the problem shows up.
In my recent years I have developed some astigmatism, but I can still do them without difficulty.
As it happens, I also can't focus on the images in TFA after crossing my eyes to get the shimmer the author refers to.