Literally, "sanpaku-gan" (三白眼) translates to "three whites eyes". It refers to how the human eye can be divided up. Sanpaku is when you can see three whites: on the left side of the eye, the right side of the eye and either above or below the iris.
In his 1965 work You Are All Sanpaku, Ohsawa explained the concept:
In a healthy newborn child, the lower edge of the iris-the sphere of color at the center of the eye-rests below the lower eyelid like a rising sun. The eye has two white areas on either side of the iris. In the eyes of a dead man, the iris turns up into the skull. If it is visible at all it has three white sides. Sanpaku. As a man becomes old or ill, as he approaches death-whether he be seven years old or seventy-the colored portion of the eye-the iris-rises to disclose white between the lower lid and the iris.
Sanpaku, Ohsawa continued, would mean that something in the person’s entire being was out of balance. Being out of balance meant the individual was, according to the author, "sick, unhappy, insane, what the West has come to call ‘accident prone.’"
Continuing, Oshawa added, "The condition of sanpaku is a warning, a sign from nature, that one’s life is threatened by an early and tragic end…" Oshawa pointed to individuals with sanpaku eyes that ranged from Martin Luther King Jr. to Abraham Lincoln.
ABOVE OR BELOW?
The superstition goes on to specify different meanings if the white appears above or below the iris of the eye. If you have a white above your iris, that means that you are possibly a danger to the outside world and unable to control your emotions. If you have a white below your iris, that means the outside world could be a danger to you.
There is a notion that people with sanpaku eyes are apparently likely to commit crimes or are insane.