beams of light

[Marijn]

When you squint while you are looking at a light, you can see a straight beam going through the light. The angle of this beam changes as you move your head from side to side. I want to know what the science is regarding these beams, please.

[Hymie]

You have a sight disorder, this could either be related to your eye(s), or the part of your brain which interprets your sight.

Best get down to your optician and have your eyes checked.

[chakka35]

Don't get worried, notafish. It's a perfectly normal phenomenon which I can reproduce anytime. I thinks it's because your eyelashes are producing a vertical slit for the light to pass through - which is why the line follows the direction of your eyelashes as you turn your head. Try this:

Look at a light, squint, get your eyelashes out of the way and you'll find the effect disappears. Moving the upper lashes is not too difficult but the lower ones are tricky. Still, when you succeed you'll see a clear light with no lines.

[heathfield]

I think Chakka's may be the right one. I notice that if you obtain the effect, then tilt your head to the side, the vertical beam stays vertical relative to the tilt.

[Marijn]

Thanks for your answers. I agree that eyelashes accentuate it, but it's still there without the eyelashes.