Eye Charts and Vision.

23 May

The Snellen eye chart was created by Herman Snellen, a Dutch eye doctor, in the 1860s. Another popular chart used during eye exams is the Tumbling E chart which features capital letter E’s facing in different directions. This chart comes in handy when young children who don’t know the alphabet are being tested, or for people who don’t know the English alphabet. Rather than say a letter, they can pick the smallest line of E’s that they can see, and say or point which way the “arms” of the E in that line are facing. Numerous studies have shown that this chart and the Snellen chart come up with nearly the same results.
Around one million people aged 40 and older in the United States (US) are considered legally blind. To obtain a driver’s license in the US, you need to have at least 20/40 vision or better. If you can read the fifth line of text on the Snellen chart from 20 feet away, you are considered to have 20/40 vision.
Cataracts, the clouding of the lens inside the eye which leads to decreased vision, affects 22 million Americans aged 40 and older. Around half of Americans will have suffered from cataracts by age 80. The medical costs relating to cataract treatment nationwide is estimated at $6.8 billion every year.

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