If it’s an emergency situation where you lost your glasses and you need to read something, all you need is a leaf and a tiny stick, or a piece of paper and a pin. Robert Krampf explains it at the Science Education Company [1].
I just tried his simple technique and it works impressively (though it’s not practical as a long-term solution).
Note to self: always carry around a leaf and a pin in case I lose my glasses.
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