Why do “light beams” appear from light sources when you squint, especially in a dark environment?
In: Biology
It causes your eye to be less spherical and creates an astigmatism (temporarily).
I know this because the light beams were always there until I got glasses that correct my astigmatism.
When you squint, you’re pushing the “tears” on your eyeball together between your eyelids. This makes the liquid bunch up enough that it creates a “bump” of water that acts as a kind of lens between your eyelids that changes how the light enters your eyes. Your eyelashes being in the way of that light also causes different optical effects which is why the “beams” usually point up and down and not side to side.
The light beams are the monsters inside reaching out trying to escape.
You know they’ve finally escaped when the bulb is blown.
it seems no one understands the question
he ‘sees’ the cone of the beam.
if not dust, what?
Hands up who else read this then squinted at their nearest light source?
Optometrist here. Looks like the topic of astigmatism has been well addressed in terms of defining what causes the light beams. It’s true that the horizontal line isolated by your eyelids narrowing cause astigmatism by pushing your tears together to form a secondary “cylinder” lens, but the question then, is why? Astigmatism is induced several different ways naturally for humans, and that is one of them. Exerting focusing effort (known as accommodation) also induced some astigmatism, which, categorically is the same kind of astigmatism induced by squinting. This astigmatism type (oriented horizontally) actually creates an optical effect which helps us see certain objects more clearly by warping them, and thus marginally enlarging them. This is not to be confused with the “pinhole effect” also created by squinting which limits light rays to make things more clear by eliminating the peripheral rays (most blurry).
Snakes and cats, alternatively have VERTICAL pupils which induce the opposite orientation of astigmatism, which help them focus on a horizontal line with objects slightly vertically warped/elongated to help them see their prey along a horizon better.
It is actually your eyelashes creating diffraction spikes. If you nudge your eyelashes while looking at a phone torch you can test it out (not too close or bright though. Also, I used to think it was astigmatism but that more causes angular slanted lines in one direction whereas diffraction spikes are from a range.
Could it be due to diffraction?
I have astigmatism and I squint in order to correct the error (light beams) you’re just describing.
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