# Will you go blind??



## Robocop (Aug 2, 2008)

After a recent trip to a tourist cave attraction I had a chance to experience total darkness. It was indeed totally dark in the bottom of this cave and the tour guide gave a few facts of "total darkness"

One of these stated facts was that scientist have shown after 4 weeks in total darkness a person will go totally blind. I tried searching this on the internet and did not see very much on this. 

So can anyone say if this is a true statement? If one does go blind after living in darkness for several weeks is it reversible and if true how does this happen? Does ones eyes simply forget how to see or does darkness somehow damage the receptors?


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## Fallingwater (Aug 2, 2008)

I don't see how this could be possible.

You may well go insane, but I don't see how staying in the dark could physically alter your eyes.


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## Robocop (Aug 2, 2008)

This was my idea as well however the guide assured me this was the case. I asked how this did not happen to people who had eye surgery and had bandages covering their eyes for many weeks....they can see after the bandages are removed.

The answer I got was in that case it was not total darkness. There is some ambient stimulation even if it is just 5 percent of light making it through the bandages. The guide said it had to be complete and total darkness such as a cave underground with zero light at all.


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## RyanA (Aug 2, 2008)

I'm willing to bet there are cases of this out there. Probably from extended confinement of "threats" to despotic leaders. Try searching Ceaucsescu and other "politicians" of his kind. I'm not sure any cases are going to support this theory though. Seems kinda odd.:shrug: I guess hes going along the lines of atrophy, but I'm not sure the eyes work like that. I think the best option would be to ask an optometrist.


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## jtr1962 (Aug 2, 2008)

Although I couldn't find info one way or the other, I tend to think this is one of those urban myths. There were people who were blind from birth and able to see fine with eye transplants. That evidently means the optic nerves and the part of the brain associated with seeing didn't degenerate from extended lack of stimulation. The eyes are the only remaining part of the equation. If not stimulated by light for a month, will the receptors in the eye no longer be able to function? I honestly don't know. If so, then an eye transplant would solve the problem.

Caves or the depths of oceans are the only naturally dark environments on Earth. Neither are really suited to long term human habitation anyway, so I doubt prolonged exposure to darkness would ever be an issue.


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## Robocop (Aug 2, 2008)

I was really facinated by the total darkness as I had no idea as to what "true" lack of all light was like. I have been in what I thought was total darkness however even so it was nothing like the bottom of this cave.

Maybe the factor involved with this would be zero light at all....no stimulation of any form to the eyes.


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## Stromberg (Aug 2, 2008)

Robocop said:


> I was really facinated by the total darkness as I had no idea as to what "true" lack of all light was like.



Isn't total darkness possible to find in more common places like cold storages, windowless rooms in night time etc? Or is there indeed something "special darkness" in caves?:candle:


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## Fallingwater (Aug 2, 2008)

If you have good window shutters (not the crappy old ones that always seem to leave a segment up...) it shouldn't really be hard to get total darkness. If no light is coming in from the outside, the inside of a closed room should be just as dark as a cave.

I *think* when you're in a cave you are mentally influenced by the setting, and so the darkness seems even darker to you.
Mind you, I've never been to a dark cave so I'm just guessing & may be completely wrong.


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## LukeA (Aug 2, 2008)

Fallingwater said:


> If you have good window shutters (not the crappy old ones that always seem to leave a segment up...) it shouldn't really be hard to get total darkness. If no light is coming in from the outside, the inside of a closed room should be just as dark as a cave.
> 
> I *think* when you're in a cave you are mentally influenced by the setting, and so the darkness seems even darker to you.
> Mind you, I've never been to a dark cave so I'm just guessing & may be completely wrong.



I think it seems darker if you don't know where the walls are or how big the room is.


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## greenlight (Aug 2, 2008)

Can I fax you a dollar for this interesting factoid?


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## Lane (Aug 2, 2008)

Robocop said:


> After a recent trip to a tourist cave attraction I had a chance to experience total darkness. It was indeed totally dark in the bottom of this cave and the tour guide gave a few facts of "total darkness"


 
DeSoto Caverns?


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## Robocop (Aug 2, 2008)

yes desoto caverns....smaller but very interesting cavern


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## gadget_lover (Aug 2, 2008)

the darkness of a cave is really different from being in a closed cold storage unit. There are always ventilation shafts and things in our normal environ.

The darkest I've seen it in a man made structure was a bathroom in a San Francisco skyscraper during a power outage. There were a dozen doors and passage ways between me and the nearest window. None of the "emergency lights" came on. And, of course, the steel partition just feet away from my eyes to further reduce the chance of a stray photon making it that far.

We stopped at the "Grand Canyon Caverns" when I was a kid, and the tour guide did the "No lights" trick too. The radium dial on my watch was the only thing in sight. 

Loved it.

As for the "will go blind"... I don;t think so. I read of cases where "blind" frogs that were born in caves, matured in caves who were able to regain sight after being brought to the surface.

Daniel


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## turkdc (Aug 2, 2008)

I recall my mom telling me something about going blind if I... Nevermind...


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## Black Rose (Aug 2, 2008)

:laughing:

When I first saw the thread title this morning, my first thought was "that thread won't last long" :devil:

I think it was last week or the week before, a thunderstorm had rolled in around 3 AM, so I had to get up to shut down the computers and close the windows. Figured since I was up, may as well go to the bathroom. While I was in the bathroom, the power went out....total 100% darkness and no flashlight in the bathroom (there is now ). Very disorienting to say the least.

If you spent a long time in the dark your eye muscles might atrophy from lack of use but I don't think you'd go blind.


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## Illum (Aug 2, 2008)

4 weeks, not likely but it will take you a prolonged time to readjust to light.
I think the guide mislead you into thinking that, it could also hold true that, since your pupils are dilated to their fullest extent, any medium of light, when concentrated to a given radius [like a flashlight] is shined upon your eyes the amount of light that penetrates into the optical nerve could potentially fry your optical nerve, thereby blinding you. 

Some concept as a webcam thats stripped to a bare CCD in the open air, and someone strobed it with a dedicated flashbulb...

For the human body to "de-evolution" to where the eyes are incapabable of sensing light...I lay my bets on at least 40 years...not 4 weeks.


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## Norm (Aug 2, 2008)

jtr1962 said:


> Although There were people who were blind from birth and able to see fine with eye transplants.


WTF Eye transplants! are you sure? I don't think such things are happening yet.
Norm


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## LukeA (Aug 2, 2008)

Norm said:


> WTF Eye transplants! are you sure? I don't think such things are happening yet.
> Norm



There most certainly are such things happening.


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## Mike Painter (Aug 2, 2008)

LukeA said:


> There most certainly are such things happening.



Cornea, yes, Eye's no.
We will almost certainly be rebuilding spinal cord injuries before an eye is transplanted.


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## Illum (Aug 2, 2008)

its refered to as Corneal transplants...
EDIT: I stand corrected


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## LukeA (Aug 2, 2008)

Mike Painter said:


> Cornea, yes, Eye's no.
> We will almost certainly be rebuilding spinal cord injuries before an eye is transplanted.


There's an experimental procedure that can give sight to some people who have been born blind. I find it hard to believe that that is just a cornea transplant.


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## Lite_me (Aug 2, 2008)

Illum_the_nation said:


> its refered to as Corneal transplants...
> Its supposedly cures cataracts...but if the optical nerve is dead I don't think any transplant could be of use


Cures cataracts? You don't really cure a cataract, and they don't do Corneal transplants for them either. They are entirely different parts of the anatomy of an eye. A cataract is a clouding of the natural lens of the eye that sits well behind the Corona. 

What is done today is that the diseased lens (cataract) is removed and a plastic interocular lens is inserted. (IOL) A 'relatively' simple procedure that's performed 1000s of times a day. 

I would consider a Corneal transplant due to disease or injury to be even more serious , especially because a donor is needed.

As far as the going blind question goes, I feel it'd be just like any other part of your body. Don't use it for an extended period of time and it's not gonna work right anymore. I feel it might take some time for the eyes/brain to recover, but recovery done properly, one should be able to see again. That may be determined by how long you were without light.


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## Marduke (Aug 3, 2008)

It's true to some extent. There are numerous cases where people who have been blind for years have been physically "fixed", but their brain can no longer correctly interpret the signals. They can "see", but it's so garbled that they are still legally blind.

This effect is a major concern when there are tumors present which either physically block light from getting into the eye, or press on the optic nerve blocking the signal. If it's left untreated for too long, even when the tumor is removed and everything is physically fine, vision may not return to near what it was.


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## Mike Painter (Aug 3, 2008)

LukeA said:


> There's an experimental procedure that can give sight to some people who have been born blind. I find it hard to believe that that is just a cornea transplant.


There are many procedures that will return sight to blind people. It depends on what causes the blindness.
Cornea transplants are just one method.

There are to date, no methods of transplanting eyes.

Rejection problems alone would be massive and the eye is the first organ to start to go bad after death.
Even with a warm body who looks OK a glance at the eyes is frequently enough to know they have been dead a while.

Further optic nerves are incapable of regeneration and hence optic nerve damage produces irreversible blindness. 

There would also be the mechanical problem of connecting the "wires" together.
"There are about 1.2 to 1.5 million retinal ganglion cells in the human retina. With about 105 million photoreceptors per retina, on average each retinal ganglion cell receives inputs from about 100 rods and cones. However, these number vary greatly among individuals and as a function of retinal location. In the fovea (center of the retina), a single photoreceptor will communicate with as many as five ganglion cells. In the extreme periphery (ends of the retina), a single ganglion cell will receive information from many thousands of photoreceptors." http://en.wikipedia.org/wiki/Ganglion_cell


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