At least for me, I notice that when I squint, my vision becomes sharper. I don’t know if this is a common thing, but I’m curious as to why it happens
In: Biology
You are making the pupil of your eye (the black hole in your eye) effectively smaller, and this makes it easier to form a focused image on the light sensitive part at the back of your eye, the retina.
To imagine how this works, think of looking at a big clock in front of you with its centre directly opposite your eye. Each numbered part of the clock fires tiny “bullets” of light at your eye, and your pupil is only one bullet wide. The bullets showing number 12, the “12 bullets”, fly from higher up, go through the pupil and hit the back of your eye at the bottom. Oppositely, the “6 bullets” fly up, through your pupil and hit the back of your eye at the top. As you can see, the image of the clock would be upside down on your retina. The same reversal happens for numbers 3 and 9, with right becoming left and left becoming right. In this process, no lens is needed because only one part of the retina sees one part of the image. If you think about it, with a tiny pupil, only the bottom of your retina will see 12, but if we widened the pupil then other parts of the retina would start saying that they can also see the number 12, which means that the image would be blurred.
Bright light also naturally makes your pupil smaller, so it is easier to focus in bright conditions than dark ones.
Instead of squinting, make an OK sign with your thumb and finger, and then curl your index finger up so that the hole gets smaller and smaller until there is only a tiny hole left. Hold that hole up next to your eye and look through it and you should be able to see more clearly.
I’ve also read that squinting can work by changing the eye’s shape. Hopefully, someone else will be able to tell us about that.
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