Comments

You must log in or register to comment.

gmtime t1_iueuix3 wrote

The smaller the opening, the less the shape of the lens plays a role. This is the same as using a pinhole camera instead of a lens to focus a photograph. This is also why bad eyesight is less of an issue when there's plenty of light, as then as a matter of speaking your iris is doing the squinting.

7

RepeatOsiris OP t1_iuevcia wrote

Thank you, this makes a lot of sense! This is ringing some bells to me, suspect I did learn this back in class many (many) moons ago.

1

macanizales t1_iuethf1 wrote

You can attribute it to a few things. Astigmatism correction due to your eyes being compressed into a rounder shape at your lens, like squeezing a slightly oval balloon from the tied and opposite ends, the deepening of your lens due to the slight compression creates a stronger magnification, and your lashes reduce ambient light that could be creating a haze over the object you're focusing on.

5

RepeatOsiris OP t1_iueu9hp wrote

I didn't realise the muscles around the eyes would be strong enough to squidge the eyes slightly into a different shape. Kind of icky but interesting to know! That all makes a lot of sense, thanks!

2

wubrgess t1_iuet1xs wrote

Your lenses suck at focusing, that's why you need glasses. Focusing just means bending the light to go to a smaller point at a particular distance. Do you know what light doesn't need to be focused? Light that's already on its way to that point. So what happens when you squint? You're actually removing all the light that requires bending so what's left is the light that would already hit your retina correctly. You're effectively turning your eye into a pinhole camera

3

Bierbart12 t1_iuev8nx wrote

So why does it become less focused when you're, let's say in a room and squinting at a PC screen?

1

sakzeroone t1_iuet6b8 wrote

It slightly flexes your eye ball and change it's shape, which is essentially what corrective lenses do

1

TheLuteceSibling t1_iuf4uu0 wrote

If you have a poorly formed lens in your eye, it won’t bend light correctly. By squinting, you focus the light like a pinhole camera rather than relying on your lens.

https://i.imgur.com/PiMO3n6.jpg

Your eyes get tired because you’ve got muscles that flex your lens, and they’re working overtime to try and fix the focus on your poorly shaped lenses.

1

Flair_Helper t1_iuf82qm wrote

Please read this entire message

Your submission has been removed for the following reason(s):

  • ELI5 requires that you search the ELI5 subreddit for your topic before posting. Users will often either find a thread that meets their needs or find that their question might qualify for an exception to rule 7. Please see this wiki entry for more details (Rule 7).

If you would like this removal reviewed, please read the detailed rules first. If you believe this submission was removed erroneously, please use this form and we will review your submission.

1

therealdilbert t1_iuf2gvg wrote

you are using muscles to squeeze the eyeballs into a different shape that focuses better. Constantly tensing the muscles can make them sore

0