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Posted on 08-09-2016
The term "Dry Eye" was first coined in 1950. For decades it was thought DRY EYE was limited to a reduction in just one component of the eye wetting/tear system called "aqueous." It was as recent as 1995 that DRY EYE was eventually recognized as a multifaceted ocular pathology which was due to decreased tear production AND increased tear evaporation. It's been estimated that 80%
of the DRY EYE complaints seen in eye doctors' offices are a result of increased tear evaporation. This article is about the latter.
There was a time when the only thing a doctor did for a patient complaining of dry eye was to tell the patient to go to the store and buy some over-the-counter ocular lubricant. The thinking was, if you throw something wet into a dry eye, it will make it better. We know a LOT more now!
Take a good look at your eyes in the mirror. Concentrate your attention on the lower eyelids. Look at the lid margins where your lashes grow. As you look farther back, you might notice little tiny pores along the lid margins; there are about 20 to 25 of them on the lower lid margin, and about twice as many on the upper lid margin. You might need a magnifying glass, and/or the assistance of a friend's eyes to see them; they're tiny. These pores are the openings from modified sweat glands that are inside your eyelids. If you gently pull down the lower eyelid and look at the inside lining of the lid, you might see faint vertical lines running up and down the back wall of the lid (hint: it's better if those lines/glands are not easily observable). Those lines are MEIBOMIAN GLANDS. They produce tiny droplets of oil, called "lipids" that very slowly exit from those eyelid pores. When you blink, the lipids mix with the watery part of the tear, called "aqueous" (and a third tear component called "mucin") to make up good quality tears. This quality tear mixture (tear chemistry) keeps your eyes "just moist enough" to maintain comfort, and help to keep your eyes healthy and seeing well. This tear chemistry bathes your eyes after each blink.
So, you see (excuse the pun), good quality tears are quite a bit more complicated than simply turning on and off the tap. That's why your doctor might tell you that you ARE making enough tears (quantity), but that your "tear chemistry" is not what it should be (quality). A poor QUALITY tear is commonly caused, or exacerbated, by MEIBOMIAN GLAND DYSFUNCTION which directly leads to DRY EYE SYNDROME.
The signs and symptoms of DRY EYE SYNDROME range from (1) none in the early stages of the disease, (2) irritated eyes, (3) red eyes and eyelids, (4) scratchy, burning and/or itchy eyes, (5) blurry vision that cannot be adequately relieved with an updated spectacle or contact lens prescription, (6) contact lens discomfort, (7) dandruff-looking flakes forming on eyelashes, (8) increased light sensitivity, (9) eyes that feel very dry, and perhaps surprisingly, (10) eyes that are excessively wet and water profusely. It's this last one that patients find counter-intuitive.
Why would a patient with DRY EYE SYNDROME complain about their eyes watering profusely? Great question! Remember, a good quality tear is made up of (1) oil/lipid, (2) aqueous, and (3) mucin. Simply put, a good tear film is sticky on the bottom, juicy in the middle and greasy on top. So let's look at what tears covering the front of the eye (the cornea) are "supposed to" look like:
The outer-most oily layer (from the Meibomian glands) keeps the tear film from evaporating too quickly, the watery layer (from the large Lacrimal gland) keeps the eye most and is protected by the oily layer, and the inner-most mucin layer (from Goblet cells in the front of the eye - cornea and conjunctiva) cause the tear to both spread out evenly across the eye and keep the tear film intact and adherent to the eye's surface until the next blink... which refreshes the tear film.
Some dry eyes result when not enough of the watery/aqueous component of the tears is produced; this is "quantitative" or decreased tear production dry eye. Some dry eyes result when the Meibomian glands do not produce enough of the oily/lipid component of the tears; this is "qualitative" or increased evaporative dry eye.
Evaporative dry eye frequently results with the eyes profusely pouring out more of the watery tear components in a reflexive attempt to re-moisten the eye. The poor tear film simply does not "sheet" or stick to the eye well while also evaporating too quickly, and the excess has nowhere to go but over the lower lid margin and down your cheek! So - "yes" - excessive tearing can and does result from DRY EYE SYNDROME.
Be certain to tell your doctor if you have any of the above signs or symptoms. Sometimes an ocular lubricant is all you need. However, frequently, diagnostic tests should be performed to determine the cause of the DRY EYE SYNDROME and thus how to approach properly alleviating the problem.
Good lid hygiene is at the forefront of care (see blog article "Brush Your Teeth & Clean Your Eyelids - July 1, 2015). Additionally, your doctor may prescribe OTC eye drops, prescription eye drops, Omega 3 fatty acids, nutritional guidelines, warm compresses and lid message, punctal plugs, oral medication, lid surgery or a combination of these and other approaches. There are many causes and many therapies. There is no "one size fits all" when it comes to how to deal with DRY EYE SYNDROME; but know... there is help available.
As usual, I am interested in your comments. Please write to me at Info@drcharm.com. I have enjoyed hearing from you and answering your questions. It's a pleasure to learn together.
Anaheim Hills Family Optometry
6200 E. Canyon Rim Rd., Suite 101
Anaheim Hills, CA 92807
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