Why does squinting help you see more clearly?

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if you're hell of nearsighted like me, anyway

― mookieproof (mookieproof), Thursday, 2 February 2006 15:25 (twenty years ago)

Something about narrowing the field of vision increases the focus, like in a camera. Or something.

― The Late Fear And The Potato Fear (kate), Thursday, 2 February 2006 15:29 (twenty years ago)

I've always assumed that squinting compressed fluid on the surface of the eye, and that if you get it just so then the curvature of the fluid on the surface of the eye when compressed acts as a lens does, tricking the eye into thinking what yr looking at is in range.

― Sick Mouthy (Nick Southall), Thursday, 2 February 2006 15:30 (twenty years ago)

it increrases DEPTH OF FIELD. the range of distance that things are in focue depends on the size of the aperture. pin-point aperture = EVERYTHING is in focus, wide aperture = barely anything in focus (why it is worse in the DARK when your pupil is fully dlated)

― Britain's Obtusest Shepherd (Alan), Thursday, 2 February 2006 15:32 (twenty years ago)

http://en.wikipedia.org/wiki/Aperture

― TOMBOT, Thursday, 2 February 2006 15:36 (twenty years ago)

the first time i got an eye exam they had me look through this disk with some pinholes in it. i had instant clear vision!

― AaronK (AaronK), Thursday, 2 February 2006 16:06 (twenty years ago)

One day while eating some cheese and crackers whilst simultaneously watching TV, for some reason I held one of the crackers (I believe it was a Ritz cracker) up to my short-sighted eyes and looked at the television through the little holes in the cracker AND MY VISION WAS PERFECT. I was amazed. I momentarily considered fashioning a pair of spectacles from Ritz crackers, but luckily realised in time that this would be just plain daft (though cheap).

― C J (C J), Thursday, 2 February 2006 16:13 (twenty years ago)

Mock Apple Glasses...

― Dave will do (dave225.3), Thursday, 2 February 2006 16:14 (twenty years ago)

the first time i got an eye exam they had me look through this disk with some pinholes in it. i had instant clear vision!

You can also do this by making a loose fist, holding your hand (thumb and first finger end) to your eye, then looking through and out of the tiny hole formed in the curl of your little finger.

― Mädchen (Madchen), Thursday, 2 February 2006 16:27 (twenty years ago)

Pinhole Glasses take advantage of the phenomenon.

― Jaq (Jaq), Thursday, 2 February 2006 16:34 (twenty years ago)

Well... there goes any productivity for me at work today :/

― Thermo Thinwall (Thermo Thinwall), Thursday, 2 February 2006 17:27 (twenty years ago)

madchen - i used to do this quite a bit in 3rd grade before i knew i really had a vision problem!

― AaronK (AaronK), Thursday, 2 February 2006 17:47 (twenty years ago)

I am unconvinced. When I had awful eye problems I used the little-aperture trick lots, and it certainly works - but mostly when people squint, their eyelids are not closing up enough to affect the functional size of the pupil. If you do close them that much, the eyelashes tend to be a problem, and it's very hard to keep them that way. Something else is going on - my guess is the pressure aids by causing a slight deformation that affects focus, more or less as Nick suggests - but I'm not completely certain it works at all. Perhaps squinting does no more for eyesight than frowning does for thinking. Possibly also just looking at the same thing for a bit gives your eyes a moment more for finer adjustments - my eyes, despite their fixed artificial lenses, so adjust some when I keep looking near or far for a while. I am guessing, obviously.

― Martin Skidmore (Martin Skidmore), Thursday, 2 February 2006 19:45 (twenty years ago)

I have new glasses today because my wife noticed last week I've been squinting a lot more at the monitor lately (w/resultant headaches).

― truck-patch pixel farmer (my crop froze in the field) (Rock Hardy), Thursday, 2 February 2006 20:24 (twenty years ago)

martin, i just looked in the mirror while squinting, and my lids cover my pupils to some degree - and eyelashes DO get in the way, which is why squinting is an imperfect solution. that and the headaches.

― AaronK (AaronK), Thursday, 2 February 2006 20:33 (twenty years ago)

I dunno... I have real crap distance eyesight and squinting does a world of good if i'm trying to read something far away*.

* far being more than 12 feet!

xpost

― Thermo Thinwall (Thermo Thinwall), Thursday, 2 February 2006 20:33 (twenty years ago)

xp -

I think the squinting part works because less light/interference gets in your eye, not because your pupil aperture is lower. ..and that may be becuase your eyelids shade your eye... The aperture thing works with cardboard, etc because it's a few mm from your eye - your eyelid is in direct contact with your eye - as Martin suggests, you can't (easily) squint & change your pupil aperture... Try looking at an LED clock at night - it's clearer when you squint or when you hold your hands up so they block out the excess light.

― Dave will do (dave225.3), Thursday, 2 February 2006 20:38 (twenty years ago)

i still maintain that Britain's Obtusest Shepherd had it right. i'm definitely looking THROUGH my lashes when i squint, and i'm testing it on printed words on bright white paper. looks like some brightness is lost, but focus is gained.

― AaronK (AaronK), Thursday, 2 February 2006 20:48 (twenty years ago)

Isn't the main problem with the squeezed-fluid-lens suggestion that if you're nearsighted, you need *concave* lenses, not convex ones?

― The Vintner's Lipogram (OleM), Thursday, 2 February 2006 21:52 (twenty years ago)

Judging by my personal glasses, nearsighted = convex!

― nabisco (nabisco), Thursday, 2 February 2006 22:14 (twenty years ago)

I was told by my eye guy that nearsightedness is usually the result of slight deformation in the eye, so that instead of being round your eyeball is football/rugby-ball shaped, and squinting roundens it up.

― Tracer Hand (tracerhand), Thursday, 2 February 2006 22:17 (twenty years ago)

Judging by my personal glasses, nearsighted = convex!

What what what are you sure? It's not just that they are curved outwards yet still thinner in the middle?

If you take them off and hold them a couple of inches over a page of text, is the text magnified or diminished?

― The Vintner's Lipogram (OleM), Thursday, 2 February 2006 22:25 (twenty years ago)

I've been told my my opto that squinting works if you're not only nearsighted but also have an astigmatism. The theory being, IIRC, because your eye is misshapen, theres a narrower area in the centre of yr field of vision where focus is better than it is at the edges, so squinting focuses on that.

I may have somewhat misunderstood the idea but it seems to make some sense.

Or um, yeah Tracer just said that didnt he. Gah I need to squint more or something!

― Trayce (trayce), Thursday, 2 February 2006 23:01 (twenty years ago)

CJ, your Ritz story upthread is one of the cutest things possibly ever.

Mock Apple Glasses...

ha!!

― tokyo nursery school: afternoon session (rosemary), Friday, 3 February 2006 00:17 (twenty years ago)

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