Experiment.

Look at the photo below,

it's to test whether you have short-sightness problem or not,

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Let's me explain in English .

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For those who do have short-sightness ,

you will see the feature of Albert Einstein,

..

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For those who do not have,

you will see Marilyn Monroe's .

p.s: That's not a fact in medic field.

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But,

try to see this photo 5 metres away from your computer.

See what is your result .