This is a very cool optical effect
Whichever dot you focus on looks purple while the others look blue
As someone whose eyes have been "settling" from cataract surgery followed by a superficial keratectomy in one eye, and has noticed my vision changing daily at various focal points, this is fascinating
Funny you mention cateract surgery. I had one eye done a bit over 3 months ago. The fixed eye makes everything look "cooler" (more blue white) than the unaltered eye (which has a much less severe cateract that "yellows" things a bit)
The illusion works as described on the organic unmodified eye with mild cataract, but no effect at all in the fixed eye.
Wild.
They are all blue in the fixed eye, and all purple in the unmodified eye, but the focused dot is a darker purple.
Kim Scheinberg
Pseudo Nym