Eye Popping!

[Aquagenic]

Hey Guys,
I was just wondering what effect diving to depth without goggles or a mask would have on the eye? Would the Aqueous or Vitreous Humor be able to equalize the pressure? Would the eye simply implode under of it. (That might hurt a little. =))

On a similiar note, what would happen if you were to dive to a significant depth wearing only goggles, without a connection to the nose?

Just some newbie questions to satiate my curious little mind. Thanks in advance!

~Picksmith

 

[JasonWelbourne]

With regards to the eyes and water, your eyes are water, so i don't think any depth would produce discomfort greater than the discomfort caused by having your eyes in contact with water at the surface.

As far as goggles go, if they weren't full of water instead of air, they would cause severe discomfort, and eventually they would break causing severe injury. This is because you would be unable to equalize the pressure of the air inside the goggles as the pressure of the water outside the goggles increased. On the water end of things, water in incompressible, so if the goggles were full of water, they would not create as pressure difference as you descened and as with descending without goggles, it would be no problem.

 

[Aquagenic]

hmmm . . . an interesting idea. But I am not sure about it. I know that your eyes have a gooey substance in them.(Aqueous and Vitreous Humor) But these are more like gel, and I am not sure if they are compressible or not. It may have a differen't effect. Also, they are sealed from the outside, so you would not be able to equalize. And a incompressable substance on the inside and out sounds like it might compress whats in between. Once again, ouch.

Wearing goggles with water in them, that would be a bit daft now wouldn't it?

Can any one back me up on this, or am I totally wrong?

Thanks for the input!


~Picksmith

 

[jome]

This should put you at ease

Fluid goggles are not a "daft" idea. We use mask/goggles to be able to see in water, not to protect ourselves from pressure. Filling your goggles with fluid will totally eliminate the need to equalize. Now if only you would be able to see with them, they'de be perfect. Luckily you can see with special goggles .

In fact, if your equalize your mask at great depth, you will have the exact same pressure on your eyes as without the mask. That's what equalizing means, you bring the outside and the inside to the same pressure by blowing air into the mask.

Now if you don't equalize or wear goggles without even the possibility to equalize (no fluid inside), then you'll have trouble. It usually get's too painful at around 4m with just goggles for me and my eyes well be all red. This is of course due to the severe under pressure which will basically act like you would stick a suction cup on your eye and try to pull it out...

So in case of barotrauma, you would actually be safer without the mask/goggles than with them. But they're handy in allowing you to see and to protect your eyes form other stuff (such as nasty bacteria or whatever)

 

[naiad]

Originally posted by picksmither
I know that your eyes have a gooey substance in them.(Aqueous and Vitreous Humor) But these are more like gel, and I am not sure if they are compressible or not.

Solids and liquids are not compressible, while gases are. Since the contents of the eye are made of solids and liquids (mostly water), the pressure would not have any effect. Only the parts of the body which are filled with air (lungs, sinuses, ears etc.) can be affected by compression.

I hope this is right! :duh

Lucia

 

[JasonWelbourne]

I guess the fact that when you press on your eyeball it hurts could lead people to intuitively beleive that the eye-ball is infact compressible, where as the question is really one of matter phase. Compression and redistribution aren't the same thing though. You could just as well believe that water is compressible because when you stick your hand in it, it moves out of the way. In any case, anything more dense then a gas is incompressible. Compressibility is the ability of matter to be fit into a smaller volume of space. If you take a cylindrical tank of water, and put a piston in it such that the piston sits on top of the water, flush with the side of the tank allowing no water to escape, the piston will exert pressure on the water. If you add weights to the piston, the amount of pressure will increase. But with water, regardless of how much weight you add, regardless of how much pressure it is under, it will not fit into a smaller volume, and the height of the piston will not change. I guess that is how dives are simulated in water filled tanks, and the ultimate reason for the experience of pressure at depth.

 

[JasonWelbourne]

Compressibility should actually be the ability of a mass to occupy a smaller volume Without undergoing a phase change. Water is kinda funny because the liquid phase is it's most compressible form whereas with other molecular substances, the solid phase is usually more dense than the liquid phase. I believe that there is actually even an ideal temperature for water at which point it reaches it's most compressed state, but as I understand compression, and it's definition it is best to consider things at a constant temperature.

 

[alein]

This is a pretty accurate description of events. It's the expansion of an object with a flexible surface that causes the surface to tear.

Consider a balloon. If you inflate the balloon until it pops, what happened was that the increasing volume forced the lining stretch beyond what its tensile strength was able to handle. The same the happens in the blood vessels, except that blood is incompressible and the amount of blood doesn't change. Instead, the beating of the heart creates a pressure gradient (high pressure in the heart, low near the periphery), which flows along the vessels in a wave. Wherever the pressure is high, the blood vessel expands, but in front of and behind the expansion is a region of contraction. The blood in the contracted areas flows into the expanded areas in addition to flowing forward through the vessel. As the ambient pressure increases, so must the pressure in the vessel (because water squeezes flesh, which squeezes vessels, which squeeze blood), and this causes the amplitude of the wave to increase. Eventually, the vessels can't expand anymore, so they tear.

In theory, if your heart never beat, and the pressure could be increased perfectly uniformly along the vessel walls, then you could dive with goggles and your eyes would never bleed.

-Adam

 

[JasonWelbourne]

That doesn't make much sense to me. The pressure difference between the water and the air space in the goggles is exerted on the surafce of the goggles. The only way to releive the pressure difference is to increase the pressure inside the goggles which could only be accomplished if the capillaries on the surface of your eyes could spontaneously swell without limit or leak into the airspace of the goggles. If your heart never beat, and the pressure could be increased with perfect uniformity along the internal surface area of the vessel wall, then if you dove with goggles and your eyes never bled, eventually the goggle plate, be it plastic or tempered glass, would crack due to the unequalized pressure differential between the air space inside the goggles and the water outside of it.

 

[Aquagenic]

Wow, those liquid goggles seem stinking awsome. Now all I need is unlimited time and money in order to buy and use them.

Does anybody have any reviews on them? Do they work well? What are the down sides? Are they durable? Any review would be nice.

Finally, yes that does put my mind at ease. Really cool stuff, thanks for the replies! I love this forum.

~Picksmith

 

[jome]

review at deeperblue

 

[Aquagenic]

Thanks Jome, that helps. I am always amazed at how much info there is already on the forum, I often overlook what I want to know. Really interesting stuff. Thanks again,


~Picksmith

 

[JasonWelbourne]

I have a homemade pair that works pretty well. They don't give me double vision, although I can't read a computer monitor with them on. They are great for doing a personal best attempt or something like that, But after I have had them on for more than 20 minutes or so, I start tasting the saline. I guess it drains through the tear ducts into the sinuses. I don't know if all saline tastes bad, or just the brand I use, but it is pretty unbearable.

 

[laminar]

A few interest facts:

Brett LeMaster did his constant weight dives without a mask in Cayman to 81-83m. His eyes were open much of the way.

Fluid goggles work and are a joy to use if you adjust them properly.

The only thing to watch out for, I would imagine, from not using goggles or a mask, is what bacteria or particles the ocean might introduce into your eye after prolonged immersion. This is mitigated by saline with fluid goggles.

High salt content in certain parts of the world feels pretty harsh on the eyes, whereas here in Vancouver it seems to almost a perfect mix (we have lots of run off from rivers)--much like saline. I often would fill my fluid goggles with ocean water because bringing a bottle of saline was a pain in butt.

Pete Scott
Vancouver, BC

 

[alein]

Originally posted by JasonWelbourne
... if you dove with goggles and your eyes never bled, eventually the goggle plate, be it plastic or tempered glass, would crack due to the unequalized pressure differential between the air space inside the goggles and the water outside of it.

I definitely agree with this. Though I wonder whether some of these space-age plastics might withstand the pressure and instead get sucked into your eye sockets... eew. No, I was assuming what would happen if you could constantly increase the pressure gradient pointing into the blood vessels in your eyes, in a uniform fashion.

I've always been a little bit unsure about the details of mask squeezes and bleeding eyes, and I'm not entirely satisfied with explanations of "this or that thing must do such-and-such a thing in order to equalize the pressure"... it just seems very inexact to me. I prefer to think in terms of the forces one is applying to an object, and have some natural laws to back up those forces being present. A pressure gradient doesn't satisfactorily explain tearing vessels by itself, since it would imply divergence of an incompressible fluid, and while the pressure pushes perpendicular to the surface, tearing is something that happens in a completely orthogonal direction... in any case, I think it's essentially the wavy geometry of the walls that allows tearing to occur.

-Adam

 

[JasonWelbourne]

As best as I can figure the only reason that blood vessels leak is because of the thinness of the capillary walls. Because a mask has a reserve volume, once you pass that, you create a vacuum inside your mask. The vacuum pressure is what exerts pressure on the capillary wall, and the fluid neither compresses or decompresses, but merely moves to offset the vacuum pressure, or releive the pressure gradient.

Having said that, the contractability of vessels of blood might well be responsible for some part of that. I don't know much about it from that standpoint. Maybe we are saying the same thing in two different ways.

I do however know how to prove or disprove your theory.

Inject a closed-system circular tube with water so that water is the only ingredient. Place it in a weighted sphere that will withstand pressures exceeding the pressure at which the wall of the tubing with submit to the vacuum. Sink it into the ocean and see what happens.

Unfortunately this experiment is substantially impossible to carry out. I will have to submit to an impasse.

 

[Aquagenic]

Jason, your experiment has piqued my interest, but as you said nearly impossible to carry out.

I agree, something about the physiology just doesn't sound right to me, but I am pretty well resolved to "not fix what ain't broken." At least in regards to physiology. Lord knows I have broken more things "fixing them" than the other way around.

One more thing Jason, you mentioned that you have "a homemade pair" of liquid goggles. How did you manage that? Is it replicable for the average free diver, or just way to much trouble? I think it would be good stuff for us all to know, even if the quality is lacking.

I look forward to your response...


~Picksmith

 

[JasonWelbourne]

There are threads on deeperblue about the homemade production of liquid goggles. I'll admit that they might be hidden in obscurity, but they are there nonetheless. I guess I pride myself in my ability to find things a little. I have to run, but this afternoon I will try to find the links to all the DIY LiquidGoggle info and post them here. Or any of a number of other people could do so. Proceduraly, I would say that it is within the capacity of the average freediver. I ordered lenses from Edmund Optics. I don't know if they are the same ones used in Eric's product, but I do know that he uses two different strengths. I purchases a pair of goggles from Wal-Mart (On discount being as swimming season is over). I fashioned holders for the lenses, although I must confess, I went about it a little differently than most people. I used cork. I find they work great. They exibit double vision on neither axis.

I am an underpaid retail worker. I live in a trailer. I can't afford to run the ac all summer or the heat all winter. I don't have the money to get a pair of eric's goggles for comparisons sake. For those of you who have money, I would strongly suggest buying a pair of eric's goggles. By doing so you are investing in freediving as opposed to some random optics company that doesn't depend on your small bucks anyway. By the time you buy several lenses, pay for shipping, a pair of goggles, and figure out how to attach them, you will have spent atleast $100 in parts and likely dozens of hours in labor and research. And that's assuming you can even figure out how to eliminate the double vision. I would like to point out that most of the people on the previous thread that built there own were unable to eliminate the double vision problem even though Eric has written a pretty good explanation of how to do it both during construction and while wearing.

That having been said. I must also warn that saline will migrate from your goggles to your sinus cavities via your tear ducts. Saline tastes bad. And quarry water bleaches my vision after 30 minutes so that everything looks washed out. It is temporary, but in any case, I don't dive with them nowadays. I use my pipe mask or a regular mask instead.

 

[Aquagenic]

Wow, there is a lot of info already out there. And to think I had to post this thread just to know that fluid goggles existed. I look forward to the day when fluid goggles are not only cheap, but the norm for freedivers and bubble blowers alike.

Here is the most informational thread that I found

http://forums.deeperblue.net/showthread.php?s=&threadid=39514&highlight=fluid+goggles

Thanks again to Eric for lending his brilliant mind to further freediving technology.


~Picksmith