The title says it all.

Somewhat technical in certain parts, but all informative, this text is a must-read for those who spend plenty of time with books (or computer screens) right in front of their eyes.

Although some theories in it are admitted to be scientifically disputed, in all, it is well worth the $40 and time I spent on it; I have never worn spectacles since.
I also noted, before buying, the staggering amount of positive feedback the book has received on Amazon. ( )