Hospital of St John & St Elizabeth WHATISBOBO

All Categories » Eye Problems » Mask Squeeze

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Aquanaut has asked me to check that my son will be able to scuba dive with a prosthetic left eye on medical grounds.

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Poor lad. Of course he can. A prosthetic eye is a solid object. As we all know, and he will learn from training, solids and liquids are not compressible with depth. Only air is. So nothing will actually happen to the eye on a dive.

However what he must watch out for is mask squeeze. This is where a tight fitting mask traps its air and the vacuum caused on descent can pull at anything within the mask. Obviously a false eye could be pulled from the socket into the mask if this happened.

He must make sure he has a loose fitting mask, and knows how to equalize it by blowing out through his nose as he goes down deeper.

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Thank you for your last advice, all is well. However, I have made a school boy error and have now got Mask Squeeze!

The white of my eyes have been very red for a week now and are now starting to itch and weep tears. How long does this take to clear up as I am quite concerned? My vision and balance is fine, but my eyes look like a Zombies eyes, not nice!

Should I see a doctor or an Optician?

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To weep a zombies tears. Poetic in the extreme, I sometimes wish I had been around in the time of Byron and Shelley. Sadly now most wordsmiths are employed writing meaningless jingles for food that kills our kids.

Right, mask squeeze- the negative pressure of the tight fitting mask sucks your eyeballs out and pops the blood vessels. Result- subconjunctival heamhorrage, or red eyes. This normally looks worse than it is, and clears in a week. But if you are now itching and weeping, chances are that you may have some allergy in there now as well. Best try Opticrom eye drops for a day or so. If that nails it then continue for a week longer. If not then see a doc asap to rule out infection.

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Recently had a diving medical with you. Have completed open water dives (max depth 9m). My left eye is very bloodshot and under my eye is a little bruised looking. Searching the internet it appears that this might happen as a result of not equalzing my mask but I thought I was doing this correctly. I am concerned about whether I should see a doctor and also whether I should dive again (in the near future or ever?)

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Of course you can dive again. This is only a minor set back, caused by a tight mask. The negative pressure as you descend caused the tiny thread capillaries on the surface of your eye to pop. Hence the bloodshot look. All you have to do is loosen your mask strap, say an inch or more. It should be loose enough to sit softly over your face, and not leave a mark when you take it off on the surface. [This is only when you try it on at home]. When you descend, blow a tiny bit of air from your nose into the mask as it tightens, and lo, all will be fine. Panic over, get diving again.

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I have a keratoconus, a thinning of the cornea in my left eye. It hasn't stopped me from diving so far, but since I'm considering going pro I would like to know if a keratoconus is really a no-no condition which excludes diving. My keratoconus is so far stabilized and does not require surgery.

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A friend rang me recently in a state of hysteria. She’d been all set to get laser surgery for short-sightedness but was declined on the basis of the same thing – keratoconus. Since the laser basically slices off layers of cornea, if it’s too thin to start with you can’t really go ahead. Apparently she used to rub her eyes constantly which has over time worn the corneas away. In extreme cases, the cornea becomes so thin that it ruptures and fluid-filled swellings form on the surface, and a corneal transplant is required urgently to avoid loss of the eye.

Diving-wise, the condition itself is not affected by pressure or depth changes. The risk is largely down to mask squeeze. If the cornea is sufficiently thin, and a negative pressure builds up in the air-filled mask space, then theoretically this could lead to rupture through the weakest point of the cornea. The current method of dealing with this is to use rigid but gas-permeable contact lenses. Gas-permeable lenses avoid the problem of bubbles becoming trapped between the lens and eye, whilst strengthening the cornea to stop it rupturing. The time course of keratoconus is variable: some are stable indefinitely while others progress rapidly or get unpredictable exacerbations, so if you’re considering turning pro then it will be important for you to keep a close eye on the condition (a pun punishable by sustained flogging; I do apologise).

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I have a question, but first a short narrative. Today I went on my second dive with 2 experienced divers in Indonesia. When we started to descend they went down very fast (faster than I was comfortable with) and my mask was on too tight, putting massive amounts of pressure on my face and forehead. I had to come up, and I came up probably faster than I should have. I stopped when I got dizzy till it went away and then came all the way up. The dive leader came up after me to check on me a few minutes later and we adjusted my mask and tried to descend again but it was still too tight so I had to come up. Over the course of the day the area around my face (only where the mask was and especially around my eyes) looked like a bruise and I have 2 black eyes… like all the blood vessels have popped or something. I have had a headache all day but other than that feel OK. I am just wanting to check with you to see if that has ever happened to anyone. I can't imagine it's DCI since I was only down for a few minutes or so and I wasn't down that far when I came up but I just wanted to double check with you.

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This is classic mask squeeze, and rest assured it has happened to many people. What happens is that the air in the mask space gets compressed as you descend, sucking the facial tissues in which can make them bleed. It looks very alarming (zombie jokes often fly around) but will settle down by itself given time, just like a bruise. As you say, it doesn't sound like DCI, in the absence of any other symptoms.

To avoid it in the future, try to exhale some air through your nose into the mask as you descend. This should stop the suction effect. If things get tight then a good mask clearing manoeuvre will sort things out.

And don't worry if you start to look like a beaten up boxer, the blood may turn all sorts of funny colours as the body breaks it down and reabsorbs it. Take some pictures in fact, as a good mask squeeze photo is hard to come by.

HJE & WHATISBOBO