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Spectacles have been around for centuries, and have a huge impact on many people's quality of life. So why is it estimated that more than two billion people aren't aware that they need them? Tim Harford considers the difference that seeing clearly makes to the world.

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10 minutes

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Mon 4 Nov 2019 04:50GMT

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An array of glasses (Credit: Getty Images)

Sources

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Smart glasses are making workers more productive

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