Just a thing weve all been thinking - http://aes.amegroups.com/article/view/3741/html
Also here - https://en.wikipedia.org/wiki/Spasm_of_accommodation There is a possibility this also applies in certain cases to near eye vision. My optometrist has mentioned there is very little writing about all these issues and theyre trying to change it now.
"The course of therapy may last weeks to several years, with intermittent monitoring by the eye doctor."
There is even a mention of PWM on wikipedia now, maybe eventually other problems will be mentioned too.
"Eye strain can also happen when viewing a blurred image (including images deliberately partly blurred for censorship), due to the ciliary muscle tightening trying in vain to focus the blurring out. " - excessive aliasing.