Hey! Who Painted the Inside of My Eyelids Blue?!

[Bronze Dog]

Just an idle curiousity I've encountered a few times in my life: Sometimes when I shut my eyes in a dark place, I see a lot of blue, kind of like static in visual "texture." This weekend, I had a particularly good example, filling most of my field of vision with blue-purple static, fairly bright at the bottom. One other memorable instance was part of an attempted (and, of course) failed attempt at a seance when I was a kid.

So, all you oculatable neurologitacious people, what causes that?

[HeyLeroy]

Viagra?

[nimzov]

filling most of my field of vision with blue-purple static, fairly bright at the bottom.

So, all you oculatable neurologitacious people, what causes that?
Hi.

Why not ask your ophthalmologist ?

nimzo

[roger]

Incipit insanity?

[Ziggurat]

Pattern recognition nerves that get bored without anything to do, and start having fun on their own.

[Axenos]

My grandfather started seeing things like that... brain tumor killed him about a year later...

Axe

[Beleth]

Sounds like what I get right before I get a migraine.

In a dark room with my eyes shut, I just see dim yellow waves move around. Kind of like the aurora.

[Meffy]

Name for the ersatz lights? "Phosphenes." Cause? All kinds things, far as I know. Rub your eyes (carefully) and you'll see more of them and brighter.

[rdaneel]

It's called "Visual Purple". It's caused by a build-up of a chemical in your eye that aids night vision. Here's a quote from a link (http://www.exploratorium.edu/snacks/afterimage.html) I found (bottom of the page)

For up to 30 minutes after you walk into a dark room, your eyes are adapting. At the end of this time, your eyes may be up to 10,000 times more sensitive to light than they were when you entered the room. We call this improved ability to see night vision. It is caused by the chemical rhodopsin, in the rods of your retina. Rhodopsin, popularly called visual purple, is a lightsensitive chemical composed of vitamin A and the protein opsin.

You can use the increased presence of rhodopsin to take "afterimage photographs" of the world. Here's how:

Cover your eyes to allow them to adapt to the dark Be careful that you do not press on your eyeballs. It will take at least 10 minutes to store up enough visual purple to take a "snapshot." When enough time has elapsed, uncover your eyes. Open your eyes and look at a well-lit scene for half a second (just long enough to focus on the scene), then close and cover your eyes again. You should see a detailed picture of the scene in purple and black. After a while, the image will reverse to black and purple. You may take several "snapshots" after each 10-minute adaptation period.
ETA: I also found another interesting tidbit in my search. It turns out if you use red lights at night, you can retain your night vision, since visual purple is not affected by red wavelengths. I'll have to try that.

[Avita]

Phosphenes! So that's what they are - it's nice to know after all this time. Now, does anyone know how to make them stop? I see them all the time - at night, I have severe difficulties seeing stars because I've always got some random fluff in my vision. And before anyone asks - I've been to the opthalmologist, and I do have astigmatism, but this is apart from that.

[wollery]

Get someone to hit you on the head, then you'll see stars! :p

Seriously though, buy a decent pair of binoculars or a telescope. If you have enough money you can buy a tracking drive and a CCD to mount on the back of the telescope, stick them outddors, connect them to your computer and then you can happily sit in a warm, well lit room looking at stars. No night vision problems!

Besides, in your opening post you say it happens when you shut your eyes in a dark place.. I can't imagine that you'll see many stars with your eyes shut. :rolleyes:

[rdaneel]

Besides, in your opening post you say it happens when you shut your eyes in a dark place.. I can't imagine that you'll see many stars with your eyes shut. :rolleyes:

Um, Avita wasn't the OP, and didn't say anything about closing his(her?) eyes.

[Bikewer]

Back during the height of New Age silliness, there were folks selling a low-voltage mask sort-of-thing that you put over your closed eyes. The current stimulated phosphenes, and you got a cheapie light show. It was supposed to be transcendant...

Or, you can turn off the lights in your bathroom and let the shower fall on your eyelids...Supposed to work just as well.

Picasso once said (in response to a question) that if he were locked in a jail cell with no light and no artists materials, he would rub his eyes and watch the play of lights thereby produced.

[ZirconBlue]

ETA: I also found another interesting tidbit in my search. It turns out if you use red lights at night, you can retain your night vision, since visual purple is not affected by red wavelengths. I'll have to try that.

Is that why military flashlights come with red lenses?

[The Kilted Yaksman]

Somewhat related to the above. Why, when I close my eyes, do I almost always see, in the center of my focal point, what appear to be small horizontal bars of flashing light? Almost like very 6 or 7 distant flourescent tubes flashing on and off. I've seen this for as long as I can remember...

[Ziggurat]

Pictsies. Pictsies painted the inside of your eylids blue.

(Pictsies should not be confused with Pixies, but are Celtic fairies who paint themselves blue and spend most of their time getting drunk, fighting, and stealing things, in no particular order).

[HeyLeroy]

Is that why military flashlights come with red lenses?

Yep. I used to have a red lightbulb in the lamp by my bed, so I could read while my (now ex-) wife slept. It works like a charm. No, wait, bad analogy. It works.

[AmateurScientist]

Is that why military flashlights come with red lenses?

Yes. Whenever one is "tactical," meaning training or operating under conditions which are hostile or simulations of hostile activity, one uses light discipline. As it is often that leaders in the field must consult maps and field manuals and orders, one uses the red light to preserve one's night vision. Also, the red light can't be seen from as far away as white light can.

Pilots use red lights to read maps, flight plans, and approaches at night and to light their instruments as well, for obvious reasons.

AS

[TX50]

A "field expedient" we were taught if you only had a white torch (flashlight) bulb was to let it shine through your fingers.

[Checkmite]

When I was quite young, I noticed that whatever I looked at something dark, if I "afocused" my eyes, I would begin to detect a very faint sort of static, little pixel-esque things darting hither and thither and yon. I told a neighbor lady about it, and she said they were "orgones" or something like that. Whatever.

Known about the phosphenes for a while, though - cool stuff your brain does.

ETA: What my neighbor described as "orgones", by the way, is actually the blue field entoptic phenomenon (http://en.wikipedia.org/wiki/Blue_field_entoptic_phenomenon).

[Avita]

Get someone to hit you on the head, then you'll see stars! :p
Thanks ever so much, but I think I'll pass ;) I used to entertain myself as a child by just looking at the visual effects in front of my eyes. Sometimes it looks like fine, glittery, multicolored snow softly falling - very beautiful.

Seriously though, buy a decent pair of binoculars or a telescope. If you have enough money you can buy a tracking drive and a CCD to mount on the back of the telescope, stick them outddors, connect them to your computer and then you can happily sit in a warm, well lit room looking at stars. No night vision problems!
Not enough money, I'm afraid, but I'd seriously like to try it out if at some point in the future, I can. Also, I have had occasion to use night-vision goggles, binoculars, telescopes (including professional ones at an observatory), and simply going up high in the mountains. While I can see more of the stars with these things, I continue to have problems. The patches of light and dark created by my nervous system "cover up" the real stars, so that it takes a lot of effort for me to first, locate even quite bright stars, and second, keep seeing them.

Besides, in your opening post you say it happens when you shut your eyes in a dark place.. I can't imagine that you'll see many stars with your eyes shut. :rolleyes:
Not my post, but good advice nonetheless :D

[wollery]

Umm, yeah, not sure what happened there. Sorry, temporary mindfart. Or something. :o

Actually looking back at the post Avita made just before mine I realise what happened. Avita's post reads like a "thank you for the responses" post. I just assumed that s/he had made the OP without checking. Yes, I am a total prat sometimes! :boggled:

[Yuri Nalyssus]

Sometimes when I shut my eyes in a dark place, I see a lot of blue, kind of like static in visual "texture."This is caused by a build-up of the spice melange in the system and is common in fremen warriors. How are you in desert conditions?

Yuri

[Meffy]

I told a neighbor lady about it, and she said they were "orgones" or something like that. Whatever.
If she said orgones rather than phosphenes, it sounds as if she had been exposed to Wilhelm Reich's wacky world.

[luchog]

Is that why military flashlights come with red lenses?
Partly. The other reason is that blue/green wavelengths are more visible, and visible at longer distances than red; so the use of red light helps prevent detection.

Interesting note, military flashlights come with multiple colour filters, red for normal use, blue for long-distance visibility, and green for map-reading, since blue and especially red light can obscure certain markings in standard military maps. Military vehicles also use green lights internally for the same reason.