The Geeks' Guide to World Domination by Garth Sundem

Author:Garth Sundem
Language: eng
Format: mobi, epub
ISBN: 9780307450357
Publisher: Crown Publishing Group
Published: 2009-11-10T22:00:00+00:00

AT-HOME EYE EXAM

Have years of monitor viewing blended your optical rod cells into slurried mush? Or perhaps your myopic vision is due to late nights spent reading manga by the light of a single LED held tented under your covers? Still, there remains hope that you, dear geek, have bucked the odds of your caste and retain ocular function. Wanna find out? Due to Hermann Snel-len, you can.

Snellen's chart, which he developed in 1862, is rather deceptively low-tech; what looks at first to be a receding series of random letters is actually quite specific, including the set height and width of letters at exactly five times the width of the line used to draw them (and the width of this line equaling the gap in the letter C). Snellen's goal was to measure a person's sight relative to what a normal cross section of the population can see; thus, 20/20 vision means you see stuff at 20 feet that most people see at 20 feet and 20/40 vision means that what you see at 20 feet, others see at 40 feet (and means you should consider increasing the font size with which you usually interact).

To get a very rough estimate of your visual acuity, hold this book at arm's length (or otherwise place it about 2.5 feet from the tip of your nose), cover one eye, and start reading letters from the top. The smallest row you can accurately read determines your acuity. While each state is different, if you have less than 20/40 vision in both eyes, you may have to jump through hoops to receive a driver's license; if neither eye is better than 20/100, you may not be able to get one. If your maximum acuity is no better than 20/200, you are legally blind.

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