See, one of the problems with Dry Eye is that everybody calls it Dry Eye when dryness may or may not actually be the problem. Eye doctors and patients use the term Dry Eye as a kind of catch-all to describe anything and everything that could possibly go wrong with your tears. There are actually quite a few things that could go wrong, and in fact probably have gone wrong, with your tears.

Usually, if you want to solve a problem, it helps to know which problem you have. Of course, you could walk around with a hammer and wherever you see a problem, hit it with the hammer. But the chances are, you are not going to fix your TV or change a light bulb very efficiently with the hammer.

So, let’s attempt to understand the problem before we select the tools.

Tear problem #1: You’re not making enough of the watery part of your tears.

Truly dry: Now we’re talking dryness. This really is "dry eye", if you agree with our logic that absence of wet = dry. Your lacrimal glands (the things in your upper eyelids) are seriously misbehaving themselves. They just aren’t pulling their weight at all — they are underproducing tears. This is a problem.

How do I know I have it? Good question. There is a test called Schirmers which you undoubtedly know all about by now. (If you don’t, this is where they stick a pre-measured strip of paper in your lower eye and wait to see how much tears it soaks up in 5 minutes.) You may or may not know by now that it is controversial. To anaesthetise or not to anaesthetise? How should the test be performed? Is it reliable? It figures, you moan. The one standardised test that could actually tell me whether I’ve got the all-important problem, and doctors are too busy sitting around debating the technicalities of whether and how it works to bother finding a way to ensure it WILL work. — We of course are of the opinion that you should be anaesthetised and left for about 5 minutes for the anaesthetic to take effect. Then we think they should blot the excess anaesthetic drop otherwise the first 10mm of the strip are going to soak up the drops, not your tears. But anyway, however the test is done, if you score less than 10 you’re almost certainly not producing enough aqueous tears. If you’re a lot less than 10, you’re in real trouble. If you’re 30, they probably did the test wrong. If you’re anywhere between 10 and 30 they might have done it wrong and you might actually be less than 10 but you won’t know. Bottom line, you will probably only find out if it’s totally obvious from looking at your eyes because they’re dry as a bone, and/or you treat your eyes as though you have this problem and the treatment helps.

So why aren’t my lacrimal glands behaving? You could be taking medications that affect your tear production. If you have ever looked at the side effects lists on medications... well, an awful lot of them mention dry eye as a side effect. Or, you could have a disease that damages the lacrimal glands — auto-immune diseases are good at that. Or, you could have a hormone deficiency. We women are so lucky. You could be getting old. Or, you could have lost some of the sensitivity in your corneas by not blinking enough, wearing contact lenses too much, staring at the computer too much, or (drum roll please) having laser eye surgery. Often, we think what happens is that you had a little bit of a problem from some of the other reasons, but it wasn’t diagnosed, or it wasn’t serious enough to diagnose, and then surgery (which basically severed some of your nerves and vaporised parts of others) pushed you right over the edge into full-blown Dry Eye.

So what DO about it? Have a look at our page on dry eye treatments. The standard methods are supplementing your tears by using fake ones from the pharmacy, and trapping your tears by plugging the drains that they can escape through (punctal plugs), and for really abysmal drier-than-a-bone cases there are some experimental treatments aimed at stimulating aqueous production. At the same time, you need to tackle the other problems, because chances are you have one or both of those too. Finally, you need to review medications you’re taking and make sure they aren’t interfering.

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Tear problem #2: They’re evaporating too fast

Okay, so maybe I’m making plenty of tears, but they’re disappearing as fast as I can make them. I can’t keep up. On the other hand maybe I’m not making enough tears, and even the few I am making are disappearing as I speak. Help!

How do I know this is happening? Probably from a Tear Break-Up Time test. It’s a stupid name for it (since what they really mean is evaporating) but basically, they put a little dye on your eye and look at you through the slit-lamp and start counting. The dye is attracted to dry spots, and when dry spots start appearing, that’s called tears breaking up (evaporating). As soon as that starts happening they stop counting. If they made it to 10-15 seconds or so, it’s working something like normal. If they didn’t, it’s not normal. If like most of us you’re down around 1 second or less, well, you’re in real trouble, as if you didn’t already know. The other way you will figure it out is just empirically: If you’ve done everything you can to make sure you have enough tears, but you’re still going dry, chances are it’s because the tears are evaporating faster than you can make or supplement them and trapping them with plugs doesn’t help because it only prevents them from draining out through the puncti, not evaporating.

So why are they evaporating too fast? First, remember when we were talking about the lipid layer of your tears? That’s what keeps your tears from "breaking up", i.e. evaporating, i.e. floating off into the air. So, if your tears are evaporating too fast you don’t have enough oily stuff. This is made by your meibomian glands. They may be making it but it’s stiffening up and getting stuck and not being secreted properly onto your eyes. That’s called meibomian gland dysfunction (MGD) and is particularly common if you’ve got blepharitis. Second, if you’ve got any tendency towards too much evaporation, or you haven’t got very many tears in the first place, environmental facts will contribute to the evaporation. Heat and air conditioning dry the air and suck moisture from your eyes. Dry climates make it worse (now’s the time to buy that holiday home in Florida). Third, if your eyes are just getting over-exposed to the air, this will also result in too much evaporation. Strangely enough, it seems many of us sleep with our eyes slightly open (funny, never used to do that before my surgery) and the massive surface evaporation is what dries your eyes out so badly at night.

So how do I keep them from evaporating? See our page on dry eye treatments. First and foremost is making more of the stuff that keeps them from evaporating — the oily stuff (lipids) that the meibomian glands produce and keeping your lids nice and clean so the glands don’t keep getting clogged up. Lid therapy (hot compresses, lid scrubs and lid massage — don’t do these without reading the instructions) does all of those things. Some medications like doxycycline are really helpful for this, and so can some nutritional supplements. Second, you can make a nice friendly environment that at least doesn’t increase evaporation: Keep your house humid, which means not overdoing it with the heat. Same with your car — don’t overdo air conditioning in summer. Third, since nights can be the worst, slap stuff on your eyes to make it impossible for tears to escape: special ophthalmic gels are good, and eye guards, even goggles if you can stand it.

Tear problem #3: They’re not sloshing around and sticking on your eyes the way they should.

Chances are, you have one or both of problems 1 and 2 anyway. Whether you do or not, you might have this problem too. In fact... most of us seem to have this problem after LASIK, and some after PRK, anyway. I won’t pretend to really understand it (after all, if as I mentioned when we talked about mucins, the scientists don’t really know either, how should I?) but I will tell you as much as I think I sort of know.

How do I know this is happening? Remember when we were talking about the sticky part of your tears — the mucin layer, which is between the watery part of your tears and your eyes themselves — the part that actually makes your eyes wet? For some reason you either don’t have enough or what you have isn’t doing its job properly. There are tests of some kind for this but they don’t seem to be very common and your eye doctor may cross his eyes when you start talking about the assays you looked up on Medline. So most people figure this out empirically: I’m using drops and/or plugs so I have watery stuff (aqueous), and I’m making enough oily stuff (lipid) with my lid therapy and doxy, and my eyes aren’t wet, ergo, I might not have enough sticky stuff!

To be fair, that’s not the only reason your eyes aren’t staying wet — we think, anyway. Chances are the laser left your corneas a little bumpier than it found them. When your eyelids open and shut, trying to push tears around, not all parts of your cornea are getting a good deal. The valleys are filling with tears and the mountaintops are probably getting kind of dry, especially when you’re staring at your computer too long. (Take a little break to do some nice long complete blinks... there, that’s better.)

Why does it happen? Remember now, we said mucins are rocket science. We don’t really know. There are abundant theories about how the surgery disrupts the goblet cells that produce the mucin layer. But it’s all kind of foggy, and there doesn’t seem to be much information available that sounds helpful in trying to do anything about it or that would change how we are already treating it.

So what do I do about it? Some people say topical steroids to get those little goblet cells to make more sticky stuff, and others say steroids make the problem worse. Naturally. Now, in practice, a great many of us have benefited from a few select brands of artificial tears (none of which are available at Boots or your local pharmacy, of course) and we think it’s partly because these ones supposedly help the mucin layer in special ways nobody else’s patent is good at. See our page on dry eye treatments for more details.