Cosmic eye flashes and flash phenomenon

Cosmic eye flashes and flash phenomenon 0

It seems like I’m hearing more and more patients describe light streaks occurring in their eyes. It could just be chance though. The way they describe these effects pretty much tells me what’s happening (helps me diagnose) and rarely is it anything serious (there are other vascular problems that could cause strange vision problems like a TIA). What patients are telling me about is their ophthalmic migraines whether the patient knew what it was or not. The strange thing is we usually think of the word migraine as causing pain in our head but the eye doesn’t have any pain when this happens. It’s interesting that the cause of this visual phenomenon is thought to be the same cause as the headache type migraine…a vascular fluctuation.

But there are other conditions that can cause light to seem to be inside the eye and not outside. There’s one called a pressure phosphene. You can create these on your own anytime you want. Just press on your eye. It’s easiest to press on the temporal side and then notice the dark circular spot that appears in the nasal part of your vision but it works both ways. That effect has even been used to estimate the intraocular eye pressure and there’s even a simple instrument that is made to do that but it’s accuracy is questionable. You can do this with your eyes open or closed. You can also rub your eyes and get other visual patterns. What’s happening is the photoreceptors are being stimulated, not by light, but by mechanical pressure which then makes those photoreceptors send a signal to your brain as if there was light, or at least an interesting visual pattern…not like a flashlight kind of light.

What is really pretty cool is what the astronauts have described as flashes. As an aside, to be considered an astronaut in the US you have to go up at least 50 miles but that may not be high enough to get cosmic flashes. The astronauts that have orbited the earth have described some really interesting visual phenomenon that has been attributed to cosmic particles that pass through practically anything and can cause a lot of problems with equipment. Astronauts from the Apollo program and more recent ISS orbiter have noticed this. Here’s a quote from astronaut Don Pettit,

“When a cosmic ray happens to pass through the retina it causes the rods and cones to fire, and you perceive a flash of light that is really not there. The triggered cells are localized around the spot where the cosmic ray passes, so the flash has some structure. A perpendicular ray appears as a fuzzy dot. A ray at an angle appears as a segmented line. Sometimes the tracks have side branches, giving the impression of an electric spark. The retina functions as a miniature Wilson cloud chamber where the recording of a cosmic ray is displayed by a trail left in its wake.”

There’s also a certain area above the atmosphere where the astronauts orbit called the South Atlantic Anomaly. When they reach that area they get more cosmic radiation compared to the rest of the orbit apparently due to a change in the magnetic field surrounding the earth. Of course this radiation is being studied but one of the odd ones is with the Phantom Torso and before that there was the the Apollo Light Flash Moving Emulsion Detector (ALFMED).

If you see flashes of light yourself, the likelihood of it being innocuous (harmless) is pretty good. But then, there’s a small chance it’s a retinal problem that needs to be treated which is why patients with any complaint of flashes should be dilated to rule out the bad stuff.

Here are a few links to some of the astronaut web pages that are kinda interesting to read:

http://www.universetoday.com/94714/seeing-cosmic-rays-in-space/
http://blogs.nasa.gov/letters/2012/04/19/post_1334853361737/

And here are a couple of images of what some might “see” when they have a visual migraine:

visual aura

visual aura

visual aura1

 

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Vision misbeliefs won’t die

Vision misbeliefs won’t die 0

I’m still reading my book, The Eye: A Natural History, and finally in the last chapter. Wow, the information in it isn’t something that I can just take with a grain of salt. The reason it’s taking so long to finish is because I’m looking up so much about what I read in it. Vision and how the eyes work…there are still some mysteries to us and that mystery goes way back thousands of years. If we didn’t have to think about how things worked and went on our merry way, would we be any better off? Of course not, that wouldn’t be human (because of our curiosity for answers) but the fact that 50% of college students think that light goes out of our eyes to see rather than coming in to our eyes is just hard to believe. Superman eyes? Really, there’s a study that showed half of the college students surveyed think light comes out of our eyes so that we can see.

This is called emission theory. Not sure why it’s called a theory in wikipedia. But it was a theory hundreds and thousands of years ago. One of our great philosophers believed that, Plato. I can’t imagine what people thought a thousand years ago but things still persist. Things and thoughts were written down so that makes a lot of what someone believed to have a persistency….because it’s written down. The information does not go away or get retracted. It’s like some news reports we hear or read where something sensational happened and it made headlines. There are many occasions where the later final report clarified what actually happened in that sensational story but didn’t make headlines, rarely ever makes headlines or is even reported….unless it’s another sensational story.

Why would 50% of college students think that light comes out of our eyes to see things? I’m beginning to really wonder if Superman does have anything to do with that. Maybe there’s another situation that might reinforce this which is when a little baby plays peekaboo. If their eyes are covered they think the other person has disappeared. They don’t understand object permanence but does that linger into college in some other way?

Another interesting experience is seeing the reflection of light come out of an animals eyes at night. It’s called eyeshine. You probably know what that looks like….beams of light coming out of a cat, deer or a raccoon’s eyes. Perhaps those animal reflections are unexplained to younger people so they might believe light does come out of an animals eyes to see better. And in reality, it does come out but only because light was shined into their eyes. They have interesting retinas with tapetum lucidums that give their photoreceptors a second chance to receive light by it reflecting back instead of the light just being absorbed. Even humans have reflecting retinas, “eyeshine,” that give us a red pupil after a camera flash. See my other post about that.

Is this light coming out of eyes related to the so-called “evil eye” where one could inflict some torturous occurrence to another by staring at them? What eyes say to others is another story but you can get the feeling when someone is giving you that look. They aren’t sending any light out of their eyes to you though.

One other misconception I want to mention is that you can still drive a car if you’re dilated! I wanted to get that in here. So many times patients ask me if they can drive home after I dilate them. There are a few exceptions to this but for most people dilating isn’t anything to worry about, driving or not.

And finally, light does not come out of our eyes to see objects. It comes into our eyes. You knew that.

A website with a fun read about ancient belief of light coming out of our eyes.

Here are some cool eyeshines (color of the reflection has to do with the angle and mineral structure):

frog eyeshine deer eyeshine spider eyeshine

cat eyeshine

cat eyeshine

 

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