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July 26, 2007 8:43 AM   Subscribe

I'm seeing red. Does anyone know why?

Occasionally (like last night) I will suddenly see a bright red dot where there is no reason to see one. It looks like a red LED or a laser sight on a gun. I've seen them in full daylight and at night. I don't remember if I've seen the dots anywhere other than while at home.

The dot is never in the center of my vision, and it doesn't last long. Blinking usually makes it go away.

It doesn't happen often, so I haven't discovered a pattern to it. Last night I was in bed and it was dark, save for the moon. In the corner of one window I saw a bright red dot. It disappeared, then came back a few seconds later. It disappeared again and didn't return. I don't believe there's anything prismatic about the window. Any thoughts?
posted by bryon to Health & Fitness (13 answers total)
Personally, I'd suggest seeing an eye doc. Sounds kinda like retinal trouble.
posted by aramaic at 8:49 AM on July 26, 2007

is it an eye floater? i have one of those, but its not intermittent like you describe.
posted by uaudio at 8:53 AM on July 26, 2007

Please see a doctor (an opthamologist, not an optometrist) quickly. IANAD, but it could be a retinal detachment, which can lead to permanent blindness in that eye.
posted by j at 9:16 AM on July 26, 2007

Burst blood vessel? Get thee to a doctor.
posted by KokuRyu at 9:23 AM on July 26, 2007

I see from your comments you have migraines which are well controlled by herbal supplements (thanks for the tip about butterbur, I hadn't heard of that), and I would guess these red spots are very slight scintillating scotoma.

Scintillating scotoma are reported in various colors, and commonly shift in color. Color perception is apparently often distorted in people with migraines, and the pattern of distortion can evidently vary with the type of migraine, and the degree of photophobia. In particular, migraine sufferers who do not experience an aura can have reduced perception of blue. If this fits you, then perhaps its not too surprising your scotoma would be red if your perception of blue is blocked.
posted by jamjam at 9:55 AM on July 26, 2007

First, absolutely get to an eye doctor.

But -- and I know this sounds silly -- have you considered the possibility that one of your neighbors has a child who enjoys playing with a laser pointer?

After all, you don't recall seeing this outside your home, you're describing what a laser pointer looks like (even in the daylight), and a bored kid with a laser pointer would probably flash it into your window at random times when you're in the room (or might be) because he finds it funny.

So doctor first, but if they find nothing, consider the possibility of a wacky kid neighbor.
posted by davejay at 9:56 AM on July 26, 2007

Nthing the possibility of retinal detachment. See a doc NOW.
posted by scody at 10:35 AM on July 26, 2007

If you can tolerate a bit more about perception of blue, bryon, after I posted my answer, it occurred to me to wonder whether reduced perception of blue was one of the bad things migraines of a certain subtype do directly to sufferers, or was instead one of the ways the brain copes with migraines, perhaps even defends against their occurrence.

If it's a defense, it seemed to me Viagra, since it causes increased perception of blue, might give rise to migraines in these cases; whereas, if it's a mere direct effect of the disease, it probably wouldn't.

I found a report of a 2003 paper in Brain, titled Migraine can be induced by sildenafil without changes in middle cerebral artery diameter which says that Viagra can indeed cause migraines, and they did restrict their subject population to migraineurs who do not have auras.

Perhaps this could help to explain your bright morning photophobia.
posted by jamjam at 11:51 AM on July 26, 2007

jamjam, that's really interesting about migraines and color perception. I do have auras with (most of) my migraines, I see blue just fine, and I'm not taking Viagra (place macho virility comment/joke here). I do seem to have slightly off color perception; I've had "discussions" for years with various folks about what color something is. Blues and greens must look a little different to me than they do to others.

davejay, there is, in fact, a kid across the road who I would suspect of such a foul thing, but he wasn't home last night. Previously, I had worried about my wife's former significant other, who was entirely too well armed for comfort and had stalked her for a year. But he's out of the picture, too.

To all, I should note that by "occasionally," I mean this happens maybe every month or two and has for about seven years (which, perhaps not incidentally, is when I started having migraines).
posted by bryon at 12:14 PM on July 26, 2007

The paper I linked to in my first post says that , in contrast to migraineurs w/o aura (MOs), those with aura (MAs) tend to have reduced perception of red.

Arguing by analogy with blue and the MOs, you could be blocking perception of red because red tends to cause migraines.
posted by jamjam at 1:39 PM on July 26, 2007

I've had ophtalmic migraines twice. I'd see a bright white light with hints of color, like a dot at first but it grew, moved left or right and went away in about 20 mins. It didn't hurt, did not follow nor was it followed by headaches or regular migraines, but it was annoying as hell. Maybe what you have is another type of eye migraine?
BTW, you should absolutely see an eye doctor to get retina issues and problems out of the way, but also see a neurologist, as eye migraines occur in the brain.
posted by AnyGuelmann at 1:51 PM on July 26, 2007

See a eye doc. I was seeing a bright blue flashes or white small dot in my vision intermittently. They only appeared when i was concentrating on a single spot for a period of time (like when I was watching TV). It turned out to be a retinal tear (not a full blow detatchment) which required laser surgery. A small tear can lead to a retinal detachment, but a full detachment can be prevented with a quick surgery.
posted by senador at 4:09 PM on July 26, 2007

Another try, if you will, at explaining the redness of the spot.

Scotomas vary in color, and are often reported to change color or even iridesce. Scotomas are thought to result when the optical cortex of the brain impinges upon its container as it swells.

If you are one of those migraineurs with aura (MAs) who tend to have reduced perception of red, bryon, then the neurons of your optical cortex associated with perception of red probably have a lesser rate of firing in ambient light than they would if you were not an MA. That means they are probably less fatigued than they would normally be, so that when your optical cortex is stimulated by direct mechanical impingement rather than its usual (red-impoverished in your case) input from other nerve cells, the unfatigued cells responsible for red contribute more to the resulting signals than others, and this biases the scotoma strongly toward the red.

If so, then scotomas of migraineurs with aura should tend to be reddish, and those of migraineurs without aura should tend to be bluish.
posted by jamjam at 4:28 PM on July 26, 2007

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