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Recently, I was having an eye exam and admitted to squinting my eyes to sharpen blurred edges. Later, while waiting for the dilation to set in, my brother (a would-be pharmacist fresh off an anatomy course) was telling me about how vision works.

As a non-scientist, here's as much as I gathered:

  • The pupil allows light into our eyes.
  • The lens bends and shifts to focus that light against our retina.
  • The retina translates this light-information into signals via the optic nerve.
  • Something about brains, and then sight!

So, my question is, if the lens being bent and shifted inside of our eye by muscles is how our eyes focus, why do those of us with poor vision squint? Surely it can't be that by narrowing my field of vision I'm consciously bending my lens.

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When I was younger (before I got glasses), I sometimes used to pinch four fingers together to make a tiny square hole and look through it. Same principle as squinting; you decrease the aperture size. – Manishearth Jan 8 '13 at 16:01

Actually it's a bit physics and biology,

It works, all right. In fact, the word "myopia" (near-sightedness) comes from the Greek words myein (shut) and ops (eye). When you squint, it's like reducing the aperture of a camera lens: You reduce the diameter of your visual lens. This gives you a longer depth of focus.

Shortly you can say, Yes by squinting your eyes you actually bends the eye lens with the help of Ciliary Muscles present in your eyes which reduce it's focal length and helps you to see with a better vision

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