Why do people squint their eyes when they can't see?

Question

Wouldn't that just make it less space to see out of?

Answer 1

This is because by squinting they actually reduce the aperture of their pupil.
Any camera buff can tell you, that as you decrease the hole admitting light (to film or retina) you improve sharpness and the depth of field, i.e. a larger part of what you are looking at comes into sharp focus.
Your eye usually does this automatically, so that in bright light your pupil contracts, the less light you have the more it dilates.

Answer 2

This squinting occurs only when the reason of poor vision is a refractive error... like myopia, hypermetropia or astigmatism...

The reason is that it causes what is called "Pin hole effect"... when a patient has a refractive error the light entering the eye doesn't all come in exact focus... it doesn't end up by a point of focused light on the retina but rather a small area.... so narrowing the enterance sharpens this focus more and more and hence improve the visual acuity... anyone with refractive error can try that at home... if you have myopia (short sightedness) or hypermetropia (far sightedenss) or astigmatism... try to take off your glasses and look at a distant object and then try to look at it through a very small hole in a paper.. you will see it clearer through the hole..

This is the basis of what is called "Pin hole test"... if you have a patient complaining of poor vision and you want a simple test to differentiate if that complain is due to refractive error or another retinal problem, just make him view the test chart through pinhole... if he sees better through pinhole then it is a refractive error.. however in case of retinal diseases (or other diseases) he will see worse through the pinhole..

So not all patients with poor vision would simply squint to see... if you see someone with cataract and trying to see something unclear in the distance you will find him widening his eyes to allow more light in... he won't squint then...

Answer 3

The process of squinting your eyes changes the shape of your eye. Usually when you can't see is is due to being near or far sighted, a shape change from the normal 20/20 seeing eye. The corrective lenses worn change the way light goes into your eye making up for the lack of shape either way.

Answer 4

squinting in high levels of light restrics light from entering the eye and obscuriing the vision, When you squint to focus its like zomming in with a camera, The picture is smaller and focused on less of an image because your eyelids are restricting the amount of the world you can see to focus on what you want to.

Answer 5

That sounds logical (and cute). The reason people squint when they can't see is because sometimes if you squint, objects tend to become more in focus. Doesn't always work but we keep trying anyway.

Answer 6

when you squint, it stretches the "lens" inside your eye. thus focusing it. This what you body does naturally (stretching the "lens") but when your eyes are bad, your eyes cannot focus properly thus you try to focus it manually. Like focusing an old camera...

Answer 7

for nearsightedness...the image that hits the retina is blurry
but if just one point of the vision enters the eye,,it is clear....
oh heck i can't explain it
you can poke a bunch of pinholes in a black mask and a nearsighted person experience the same phenomenom
i can't believe you a nurse and don't know about this... :-(

Answer 8

In order to focus and concentrate the light

Answer 9

If outdoors, to block the light, if indoors, to flatten their cornea to adjust the focus mechanism of their eyes.

Answer 10

Your Eyes can then focus more then when are fully open..... more "Eye power"