If you love crossing your eyes and giving yourself a headache, then you probably loved Magic Eye books.

First released in 1991, the books are collections of austereograms (which is nerd for “migraine”) which allow people to see a 3D image in a 2D picture.

Although austereograms have become synonymous with the Magic Eye books, the first ones were black and white and were created in 1979 by a psychophysicist named Christopher Tyler. This technique was later colorized by computer programmer Tom Baccei and compiled into one, brightly colored collection. The books were first released in Japan in 1991 and were so insanely popular that they, of course, had to be released in the U.S.

Americans freaking love it.
The original Magic Eye book and two sequels were released in 1993 and spent 73 consecutive weeks on the New York Times Bestseller List. Since then, the Magic Eye photos were put on everything from postcards to mouse pads so that you had a variety of ways to assault your eyes.

If you’ll excuse me, I need to go take some Tylenol. Happy Throwback Thursday!