blury vision below 80 FSW

**Gill Envy** · 23rd May 2006, 21:52

I've been alarmed on several dives when my ability to read my computer...my PO2!!! has become hindered by blury vision. this first happened last month during my first training dives. My instructor said i should get my eyes checked. The tricky part is that my vision varies with depth, it doesn't seem to be a problem unless I go below 80 feet, which is nearly every dive now. I don't have trouble with my vision at the surface. My first concern was that i could be one of those folks who is hyper sensative to oxygen and that my symptoms could be related to Hyperoxic Myopia (i hope i'm getting that right).

I started to come to a new conclusion when i also started realizing that my ears are getting pretty crunchy from my rebreather diving. It seems that about half way through the dive i go to clear my ears and I feel a pinch and a bit of a "water in the inner ear" sensation which persists from that point on. Aftewords for a day or two my ears are crunchy and my hearing is slightly muffled.

My latest hypothesis is that my wonderful low volume, framless mask is to blame for the eye issues along with the fact that it seems that the pressure of the surrounding sea water is not counterbalanced like it was on OC by the regulator, which seems responsible for my ear sqeeze as well. Basically i feel like i'm fighting the tendency of the sourounding sea water to give me a sqeeze, especially at depth. what i know of eyes, at least when i've fallen asleep with my arm over them, is that extended periods of relatively light pressure can temporarily cuase bluryness, so i guess it makes sense that a chronic mask squeeze could have the same effect.

Not sure if it's my imagination, but on most recent dives i've been making an extra effort to keep my mask pressurized by closing the soft palate in the back of my throat and keeping some extra air in my mask. This is a bit of a drag as it feels pretty wierd, but does seem to improve my eye sight. the wierd thing is that the amount of squeeze in my mask just did not seem adequite to cause problems.

I've made some headway with my ear issues by paying extra close attention to clearing my ears regularly on the way down...even more religiuosly than i used to on OC.

My wife has a more standard mask and has not complained of either of these problems. does anyone have any pointers...should i go back to a standard framed mask, the kind that has stiffer seal or do i have to become more accostom to holding my sinus cavity closed.

**Steve** · 24th May 2006, 00:53

Try working with the pressure inside your mask. Too much pressure can distort vision. It is hopefully something that simple

***ScubaDadMiami*** · 24th May 2006, 00:53

I'm not a doctor. So, this is only from my limited education.

Your ears sound like they have fluid in them. That is why you are getting that fullness and muffling sound for a few days after diving. The question is: How did that fluid get in there?

If you allow a squeeze to develop, your middle ear can actually pull blood and other fluid from the surrounding tissue. The fact that you have been more diligent about equalizing, resulting in this lessening, makes this sound like you have gotten at the root of the cause. Make sure to equalize early and often. Also, remember that on CCR, due to the middle ear oxygen absoption, you will want to continue equalizing after a dive for several hours.

They eye thing is a mystery to me. However, the fact that it is getting better by being on top of equalizing your mask space sounds like a clue to the solution. Why not try a dive on another mask to see what happens?

Have you been to a doctor/opthamologist that knows about these issues? Might be a good idea to get checked out.

**Gill Envy** · 24th May 2006, 01:34

Quote: (Originally Posted by ScubaDadMiami)

....
Your ears sound like they have fluid in them. That is why you are getting that fullness and muffling sound for a few days after diving. The question is: How did that fluid get in there?

If you allow a squeeze to develop, your middle ear can actually pull blood and other fluid from the surrounding tissue....

You are brilliant, that must be what is going on. I've never heard of this but it makes total sense. I'm just surprised that such a squeeze can develop without me feeling pain.

Quote: (Originally Posted by ScubaDadMiami)

Also, remember that on CCR, due to the middle ear oxygen absoption, you will want to continue equalizing after a dive for several hours.

can you please illucidate? this is news to me.

**Gill Envy** · 24th May 2006, 01:38

Quote: (Originally Posted by Steve)

Try working with the pressure inside your mask. Too much pressure can distort vision. It is hopefully something that simple

when you say work with the pressure, do you have any tips on how to do that. if i add even a little bit of air to my mask area it goes right out the seal. Is the technique i've described as holding the air up their and breathing through my mouth, like as if you were trying to talk as if you had a stuffy nose, what you are talking about. or is my mask just too loose, or the wrong mask. thanks for your thoughts.

***ScubaDadMiami*** · 24th May 2006, 03:49

Quote: (Originally Posted by Gillenvy)

. . . that must be what is going on.

It's simple. If you have something blocking the passage of gas into your middle ear, that gas space will act like any other in the body if not equalized: As you descend, the pressure will become negative. Eventally, if it becomes strong enough, it will cause blood and fluid to be sucked into the middle ear from the surrounding tissues.

You might be trying to equalize. However, if you have a cold, a low grade infection or some kind of congenital ear problem, you might not be getting enough gas through your eustacian tube to the middle ear. Equalizing harder is not the answer. You should get checked out by a diving ENT to make sure that this is not the situation.

If you find that you are not having health issues, then you are not equalizing early enough or frequently enough as you descend. Try to do so very frequently especially during the first several feet after beginning your descent (actually, even before your head goes under).

Quote: (Originally Posted by Gillenvy)

can you please illucidate? this is news to me.

Mastering Rebreathers, Best Publishing (2002), Chapter 5, page 106:

"Many rebreathers can provide breathing gas with very high FO2 to the diver. . . . This is not a problem during the dive, or immediately after surfacing from the dive. . . . [W]hen you surface from the dive, you will have this same high FO2 gas in your Eustachian tube and behind your tympanic membrane.

While you remain out of the water, the oxygen in those gas filled spaces is being absorbed by the surrounding tissues. Unfortunately, that absorbed gas is not being replaced as quickly with nitrogen. The result is a net loss of gas molecules from the middle ear, with consquent volume loss. The pressure outside the tympanic membrane becomes comparatively greater, and exerts a pressure on the membrane. This can result in painful squeeze known as middle ear oxygen absorption syndrome, with a barotrauma injury to that which might be experienced on descent if you forget to clear your ears. Because it is a slow process, it is not uncommon for the diver to be completely unaware of it until noticable injury has been sustained.

To avoid this injury, it is necessary to periodically equalize after the dive, while you are on the surface."

Drmike · 24th May 2006, 05:12

After last weeks dives and especially after the 8 hour one my eyesight was great. So good in fact that I wondered if something was wrong. It took me a while to realise that what was wrong was the fact I could see better. Slowly over the last few days its deteriorated back to is pre-dive crappy vision level and I'm wearing my glasses again.

PPO2 induced myopia rocKs!

dave t · 24th May 2006, 07:40

not sure what rebreather you are diving but are you keeping up with the bag volume? negative lung loading may cause your problem. When diving my kiss I had similar problems to you (not the eyesight bit though but with my bad eysight I probably wouldnt notice) due to the backmounted counterlungs and small volume.

just a thought

Dave

Sutty · 24th May 2006, 12:58

The oxygen-ear effect is particularly important if you go to sleep after diving - you are less likely to equalise and more likely to get problems.

The hyperoxic myopia thing is fascinating, I experienced this for the 1st time recently. I have seen one reference suggesting that the gas the eye is exposed to (ie what is in your mask) may be important as well as the arterial PO2. If this is so then if you have a BOV it may be better to take a breath of dil from this to clear or equalise a mask.

Neil

Mixaddict · 24th May 2006, 23:20

I can't speak to your eye problems, but my suspicion about your ears is that if you are fairly new to rebreather diving, you may be somewhat task loaded to the point where you are not equalizing as naturally and as often as you did with OC. Consequently, your ears are probably just getting a little traumatized. They swell and don't equalize before or after the dive quite as well. It will probably get better as you get more comfortable with your unit. Just a thought

23rd May 2006, 21:52	#1 (permalink)
Gill Envy Shearwater Copis Diver Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,209	blury vision below 80 FSW I've been alarmed on several dives when my ability to read my computer...my PO2!!! has become hindered by blury vision. this first happened last month during my first training dives. My instructor said i should get my eyes checked. The tricky part is that my vision varies with depth, it doesn't seem to be a problem unless I go below 80 feet, which is nearly every dive now. I don't have trouble with my vision at the surface. My first concern was that i could be one of those folks who is hyper sensative to oxygen and that my symptoms could be related to Hyperoxic Myopia (i hope i'm getting that right). I started to come to a new conclusion when i also started realizing that my ears are getting pretty crunchy from my rebreather diving. It seems that about half way through the dive i go to clear my ears and I feel a pinch and a bit of a "water in the inner ear" sensation which persists from that point on. Aftewords for a day or two my ears are crunchy and my hearing is slightly muffled. My latest hypothesis is that my wonderful low volume, framless mask is to blame for the eye issues along with the fact that it seems that the pressure of the surrounding sea water is not counterbalanced like it was on OC by the regulator, which seems responsible for my ear sqeeze as well. Basically i feel like i'm fighting the tendency of the sourounding sea water to give me a sqeeze, especially at depth. what i know of eyes, at least when i've fallen asleep with my arm over them, is that extended periods of relatively light pressure can temporarily cuase bluryness, so i guess it makes sense that a chronic mask squeeze could have the same effect. Not sure if it's my imagination, but on most recent dives i've been making an extra effort to keep my mask pressurized by closing the soft palate in the back of my throat and keeping some extra air in my mask. This is a bit of a drag as it feels pretty wierd, but does seem to improve my eye sight. the wierd thing is that the amount of squeeze in my mask just did not seem adequite to cause problems. I've made some headway with my ear issues by paying extra close attention to clearing my ears regularly on the way down...even more religiuosly than i used to on OC. My wife has a more standard mask and has not complained of either of these problems. does anyone have any pointers...should i go back to a standard framed mask, the kind that has stiffer seal or do i have to become more accostom to holding my sinus cavity closed. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°>
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24th May 2006, 00:53	#2 (permalink)
Steve Ladies bring a plate Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Classic Kiss MK 15.X Home Build Join Date: Feb 2005 Location: Perth - Australia Posts: 1,041	Re: blury vision below 80 FSW Try working with the pressure inside your mask. Too much pressure can distort vision. It is hopefully something that simple __________________ WARNING: I contain occasional coarse language, extreme sexual references, nudity, and adult themes, which may offend some people - Usually churchy types.
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24th May 2006, 00:53	#3 (permalink)
*ScubaDadMiami* Moderator Current Rebreather/s: Optima Other Rebreather/s: Join Date: Sep 2005 Location: Florida, USA Posts: 1,890	Re: blury vision below 80 FSW I'm not a doctor. So, this is only from my limited education. Your ears sound like they have fluid in them. That is why you are getting that fullness and muffling sound for a few days after diving. The question is: How did that fluid get in there? If you allow a squeeze to develop, your middle ear can actually pull blood and other fluid from the surrounding tissue. The fact that you have been more diligent about equalizing, resulting in this lessening, makes this sound like you have gotten at the root of the cause. Make sure to equalize early and often. Also, remember that on CCR, due to the middle ear oxygen absoption, you will want to continue equalizing after a dive for several hours. They eye thing is a mystery to me. However, the fact that it is getting better by being on top of equalizing your mask space sounds like a clue to the solution. Why not try a dive on another mask to see what happens? Have you been to a doctor/opthamologist that knows about these issues? Might be a good idea to get checked out. __________________ Howard Packer IANTD CCR Instructor Miami Beach, Florida CCRDiveTraining.com
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24th May 2006, 01:34	#4 (permalink)
Gill Envy Shearwater Copis Diver Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,209	Re: blury vision below 80 FSW Quote: (Originally Posted by ScubaDadMiami) .... Your ears sound like they have fluid in them. That is why you are getting that fullness and muffling sound for a few days after diving. The question is: How did that fluid get in there? If you allow a squeeze to develop, your middle ear can actually pull blood and other fluid from the surrounding tissue.... You are brilliant, that must be what is going on. I've never heard of this but it makes total sense. I'm just surprised that such a squeeze can develop without me feeling pain. Quote: (Originally Posted by ScubaDadMiami) Also, remember that on CCR, due to the middle ear oxygen absoption, you will want to continue equalizing after a dive for several hours. can you please illucidate? this is news to me. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°>
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24th May 2006, 01:38	#5 (permalink)
Gill Envy Shearwater Copis Diver Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,209	Re: blury vision below 80 FSW Quote: (Originally Posted by Steve) Try working with the pressure inside your mask. Too much pressure can distort vision. It is hopefully something that simple when you say work with the pressure, do you have any tips on how to do that. if i add even a little bit of air to my mask area it goes right out the seal. Is the technique i've described as holding the air up their and breathing through my mouth, like as if you were trying to talk as if you had a stuffy nose, what you are talking about. or is my mask just too loose, or the wrong mask. thanks for your thoughts. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°>
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24th May 2006, 03:49	#6 (permalink)
*ScubaDadMiami* Moderator Current Rebreather/s: Optima Other Rebreather/s: Join Date: Sep 2005 Location: Florida, USA Posts: 1,890	Re: blury vision below 80 FSW Quote: (Originally Posted by Gillenvy) . . . that must be what is going on. It's simple. If you have something blocking the passage of gas into your middle ear, that gas space will act like any other in the body if not equalized: As you descend, the pressure will become negative. Eventally, if it becomes strong enough, it will cause blood and fluid to be sucked into the middle ear from the surrounding tissues. You might be trying to equalize. However, if you have a cold, a low grade infection or some kind of congenital ear problem, you might not be getting enough gas through your eustacian tube to the middle ear. Equalizing harder is not the answer. You should get checked out by a diving ENT to make sure that this is not the situation. If you find that you are not having health issues, then you are not equalizing early enough or frequently enough as you descend. Try to do so very frequently especially during the first several feet after beginning your descent (actually, even before your head goes under). Quote: (Originally Posted by Gillenvy) can you please illucidate? this is news to me. Mastering Rebreathers, Best Publishing (2002), Chapter 5, page 106: "Many rebreathers can provide breathing gas with very high FO2 to the diver. . . . This is not a problem during the dive, or immediately after surfacing from the dive. . . . [W]hen you surface from the dive, you will have this same high FO2 gas in your Eustachian tube and behind your tympanic membrane. While you remain out of the water, the oxygen in those gas filled spaces is being absorbed by the surrounding tissues. Unfortunately, that absorbed gas is not being replaced as quickly with nitrogen. The result is a net loss of gas molecules from the middle ear, with consquent volume loss. The pressure outside the tympanic membrane becomes comparatively greater, and exerts a pressure on the membrane. This can result in painful squeeze known as middle ear oxygen absorption syndrome, with a barotrauma injury to that which might be experienced on descent if you forget to clear your ears. Because it is a slow process, it is not uncommon for the diver to be completely unaware of it until noticable injury has been sustained. To avoid this injury, it is necessary to periodically equalize after the dive, while you are on the surface." __________________ Howard Packer IANTD CCR Instructor Miami Beach, Florida CCRDiveTraining.com
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24th May 2006, 05:12	#7 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,062	Re: blury vision below 80 FSW After last weeks dives and especially after the 8 hour one my eyesight was great. So good in fact that I wondered if something was wrong. It took me a while to realise that what was wrong was the fact I could see better. Slowly over the last few days its deteriorated back to is pre-dive crappy vision level and I'm wearing my glasses again. PPO2 induced myopia rocKs! __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you
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24th May 2006, 07:40	#8 (permalink)
dave t Custom Title Allowed! Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Sport Kiss Classic Kiss Dolphin Ray Azimuth Home Build Other Rebreather/s: Dolphin Ray Azimuth Home Build Join Date: May 2005 Location: UK Posts: 610	Re: blury vision below 80 FSW not sure what rebreather you are diving but are you keeping up with the bag volume? negative lung loading may cause your problem. When diving my kiss I had similar problems to you (not the eyesight bit though but with my bad eysight I probably wouldnt notice) due to the backmounted counterlungs and small volume. just a thought Dave
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24th May 2006, 12:58	#9 (permalink)
Sutty Classic Kiss diver Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Jun 2005 Location: Glossop, Derbyshire, UK Posts: 763	Re: blury vision below 80 FSW The oxygen-ear effect is particularly important if you go to sleep after diving - you are less likely to equalise and more likely to get problems. The hyperoxic myopia thing is fascinating, I experienced this for the 1st time recently. I have seen one reference suggesting that the gas the eye is exposed to (ie what is in your mask) may be important as well as the arterial PO2. If this is so then if you have a BOV it may be better to take a breath of dil from this to clear or equalise a mask. Neil __________________ Never forget that life is a finite resource.
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24th May 2006, 23:20	#10 (permalink)
Mixaddict Always Learning! Current Rebreather/s: Inspiration Vision Evolution Other CCR Dolphin Other Rebreather/s: Inspiration Classic Other CCR Dolphin Join Date: Jan 2006 Location: Draper, Utah USA Posts: 413	Re: blury vision below 80 FSW I can't speak to your eye problems, but my suspicion about your ears is that if you are fairly new to rebreather diving, you may be somewhat task loaded to the point where you are not equalizing as naturally and as often as you did with OC. Consequently, your ears are probably just getting a little traumatized. They swell and don't equalize before or after the dive quite as well. It will probably get better as you get more comfortable with your unit. Just a thought
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