I thought this was very interesting.
I am not sure how much I believe in the theory below, but certain eye ‘expressions’ are terrifying – particularly wide staring eyes. I have seen it happen over the years in people who suffer from heavy drug addiction and/or serious mental disorders, and it is terrifying. It is usually accompanied by ranting or shouting. Whenever it happens near me – in public spaces or public transport – my body goes into full alert. I always wonder why humans instinctively react to certain body language or facial expressions, interpreting them as a threat. I assumed it was something in our lizard brain reacting to a perceived threat.
Sanpaku refers to the whites of the eye being visible on three sides. In Japanese physiognomy (or face reading), whites above the eyes denote a dangerous or violent personality (as exemplified by Charles Manson).
In western terms, sanpaku is called “scleral show” and may simply be a function of genetics, endocrine issues, aging, or surgeries like blepharoplasties.
However, seeing the whites of someone’s eyes, combined with a cold hard stare, will give you chills. It’s called a reptilian gaze. Such stares activate your limbic system, causing you to go on alert.

Your instinct to separate the two things is the right one. Scleral show is mostly anatomy, plenty of people are simply built that way and nothing is going on behind it. What sets off the alarm is the stare that comes with it, the not-blinking, the fixed focus. That’s a state, not a face. Manson had both, which is why that photo does so much work.
This is a really good point.
That explains a lot about Charles Manson and my most recent 2 exes. They both had whites visible at the top of their eyes and I should have been aware of this and never got involved with either of them.
This is so interesting! I didn’t know about that. Charles Manson has always been really scary for so many reasons but staring at the picture you shared definitely hit it on the nail. I am lucky to never have met people who had those eyes and I hope it stays that way!…