“The Wonderful Story of Henry Sugar”

This story was indeed written by Roald Dahl. According to the Wikipedia description:
Henry, an independently wealthy man who enjoys gambling, finds and
reads a doctor’s report on a strange patient the doctor met while
stationed at a hospital in India. This patient, who called himself
“The Man Who Sees Without Using His Eyes”, had the ability to see even
after the doctors had medically sealed the man’s eyes shut and
bandaged his head. The man was part of a circus act and used his
ability to make money. When interviewed in more detail by the curious
doctors he gave an account which they wrote up. The man claimed he had
been interested in magic all his life, and managed to study with Yogi
Fakeirs in India, by which he develops the ability to see through thin
objects such a paper or playing cards, and can see around solid
objects such as a wooden door if he is allowed a finger or hand around
it. The doctors decide the man could be of great benefit as a teacher
of the blind, and return to the circus, only to find the show
cancelled, when the Man Who Sees Without Using His Eyes has died.
He can see things with, say, a finger:
"Quite honestly, I don’t know exactly how it is I can see without my
eyes. But what I do know is this; when my eyes are bandaged, I am not
using the eyes at all. The seeing is done by another part of my body."
"Which part?" I asked him.
"Any part at all so long as the skin is bare. For example, if you put
a sheet of metal in front of me and put a book behind the metal, I
cannot read the book. But if you allow me to put my hand around the
sheet of metal so that the hand is seeing the book, then I can read
it."
“The Wonderful Story of Henry Sugar”
There is a dark twist at the end; however, it never happened. Dahl is simply saying what would happen "if the story were fiction":
At first, the clot seems to be stationary. Then it moves. The movement
is very slight, no more than a millimetre or two. The blood inside the
vein is pumping up behind the clot and pushing past it and the clot
moves again. It jerks forward about half an inch. This time, up the
vein, towards the heart. Henry watches in terror. He knows, as almost
everyone else in the world knows, that a blood-clot which has broken
free and is travelling in a vein will ultimately reach the heart. If
the clot is a large one, it will stick in the heart and you will
probably die. . ..
That wouldn’t be such a bad ending for a work of fiction, but this story is not fiction. It is true. The only untrue things
about it are Henry’s name and the name of the gambling casino. Henry’s
name was not Henry Sugar. His name has to be protected. It still must
be protected. And for obvious reasons, one cannot call the casino by
its real name. Apart from that, it is a true story.
“The Wonderful Story of Henry Sugar”