Where does this come from, and can I check it?

Hardening lens proteins make it harder to bend light sharply for nearby objects. The figure is taken from NIH, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a human body fact?

Yes. It sits on the Human Body shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

The lens stiffens with age and loses close focus

Hardening lens proteins make it harder to bend light sharply for nearby objects The eye focuses close up by contracting the ciliary muscle, which slackens the lens capsule and lets the lens bulge. Lens proteins cross-link over decades, so the tissue resists reshaping. Most people notice the change in their forties, when close reading needs to be held further away. It sits in Mondo's human body collection, one of 200 facts that each trace back to the reference below.

Where this comes from

NIH

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Tags: eye, ageing, lens

The lens stiffens with age and loses close focus: the short answers

Where does this come from, and can I check it?: Hardening lens proteins make it harder to bend light sharply for nearby objects. The figure is taken from NIH, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a human body fact?: Yes. It sits on the Human Body shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.