Why a dot vanishes when you look away from it: the blind spot where the optic nerve exits
30seconds
Close one eye, stare at a cross, and a dot a hand's width away simply vanishes. That is your blind spot: the place where the optic nerve leaves each eye, with no light-sensing cells at all. It sits about 15 degrees to the side of where you are looking, and you never notice it.
Drag a dot across the field, switch eyes, change the pattern behind it and slide your viewing distance. Watch the dot disappear, then watch the stripes run straight through the hole as your brain quietly paints over it.
Deep dive · 4 min
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