Airplane hallucinations?

January 31, 2009 7:15 PM

While descending in a plane, I saw strange swimming lights. What's the deal?

I had a window seat, right near the front of the plane. I began to see the lights when we were descending, specifically when we were between two layers of cloud. It was in the early afternoon today, and even though we were below one layer of cloud it was still very bright, and the ground was completely snowed over so there was a lot of light from below as well. I could still look out the window without squinting, but everything was either white or gray and my eyes didn't know where to focus.

I kept looking, though, and I started to see rapidly moving, swimming flecks. They were black and white not colored, and they were constantly in motion. It was a little like looking at a cloud of flies, but they moved faster, and never really seemed to stop. It reminded me of a sped up biology film, of bacteria or something similar squiggling around a petri dish.

I talked to a friend about it and she said that it could have been the floaty particles in my eyes, but they were moving much much too quickly, and at one point, as I was watching them go, I saw one of the usual back-of-the-eye detached blood vessels float past my field of vision, and it seemed to be "behind" of the specks, as in, the thread was in my eye as usual and the specks were storming in front of me. I also noticed that the specks were three dimensional, as in, I could focus my eyes in or out, and change what part of this particle field I was looking at. I could look further, and the specks closer would go out of focus and vice-versa.

While I was watching them, I tried closing my eyes several times, or looking inside the plane. They vanished when I was looking anywhere besides outside.

After I was watching these specks or particles or sparks or whatever they were, I began too see something else too, black shapes coming and going right around where I focused my vision. It was if I was going backwards rapidly through a tunnel.

We descended through the lower layer of cloud and they started to fade rapidly, first the black backwards tunnel part, then the specks. It might be worth noting that as we came through the cloud layer, there was still snow throwing up light from below, and at that point I could still see them faintly, but when we flew over houses and roads they left completely.

The specks, and the black tunnel bit, were in black and white, and I could focus my eyes on them. It was very different from, say, pressing on your eyes and seeing bluish-purplish-reddish blotches. I've had minor migraines, where you see a floating patch of black-white-rainbow-flashes and it's hard to focus on anything. It was different from that as well.

At the time of this strange visitation, I was a little drowsy from leaving early to get to the airport but still completely awake. I was suffering from a sinus-pressure kind of headache, but it wasn't very bad, and I've had those without hallucinating many a time. I wear glasses, I'm near-sighted, and had them on at the time of the "vision." I had not taken any medication that morning or the day before.

Any guesses, metafilter? Is there a name for this kind of thing? Has anyone experienced anything similar?

posted by Rinku to travel & transportation (6 comments total)

Blue field entoptic phenomenon

Ok, so it was cloudy and not blue sky but it is the same principle.
posted by Justinian at 7:22 PM on January 31 [2 favorites has favorites]

Potentially autokinesis, or some variant thereof. I mean, looking at a snowy landscape, in early evening, the eyes are beginning to struggle with the light levels, typically (I can't really comment on the conditions you're talking about obviously), but that sort of time autokinesis becomes more prevalent. When you can't make out what it is you're trying to focus on and all...
posted by opsin at 7:23 PM on January 31

OK, good catch Justinian, and interesting. I knew of floaters, but not this.
posted by opsin at 7:25 PM on January 31

Did anyone else on the plane notice this phenomenon?
posted by pravit at 8:12 PM on January 31

I didn't ask if anyone else saw it. No one said anything about it, anyway. Blue field entoptic phenomenon sounds just about right - I don't remember the specks moving in paths, and it the black tunnel deal must have been something else, but other than that it's right on the ball. Thanks Justinian.
posted by Rinku at 8:43 PM on January 31

I think we can get the black tunnel effect out of the blue field entoptic phenomenon, too.

As Justinian's linked page says, there are retinal capillaries in front of the retina, and

Blue light (optimal wavelength: 430 nm) is well absorbed by the red blood cells that fill the capillaries. The brain "edits out" the dark lines that would result from this absorption.

That means that the perception of cloud shadows in blue light will be muted in the part of the retina that capillaries are in front of. The fovea, however, has no capillaries in front of it, so a shadow in blue light traveling in from the periphery of your retina toward the center will suddenly appear when it reaches the edge of the fovea, since that edge is rich in blue cones.

The very center of the fovea, however, lacks blue cones altogether, so the shadow will wink out of existence perceptually at the very center of your focus.
posted by jamjam at 12:54 PM on February 1