Dry eye is a very common condition. Millions of people worldwide have dry eye. In fact, just by reading this article, you can be causing some dry eye yourself! But do read on.. We’ll get to that later.
Dry eye really boils down to one issue: the cornea of the eye isn’t being protected from the environment and drys out. This causes short-term damage to the cells on the surface of the cornea resulting in burning irritated eyes and blurred vision.
Overall, dry eye is a really simple concept. And fortunately relatively straightforward to treat. But despite being simple, there are countless things to learn about what causes dry eye and how it is treated.
The Tear Film Protects The Eye
On the surface of the eye rests a layer of liquid, oils and other things that provide a protective barrier to the eye: the tear film. This layer prevents the cornea (the front clear part of the eye) and the conjunctiva (the white part of the eye) from drying out (this layer also serves multiple other cool purposes such as helping to fight infection and feeding the front of the cornea; see also Anatomy of the Eye Made Easy). If this layer doesn’t do a good job protecting the cornea, then the cornea starts to become exposed to and damaged by environment. This is dry eye.
What Causes the Tear Film to Have Problems?
Most dry eye comes from tears evaporating too quickly from the eye. On the very surface of the tear film are oils that protect a watery layer below. These oils come from tiny little glands in the eyelids near the eyelashes called meibomian glands. These glands constantly produce these oils to coat and cover the surface of the eye like shrinkwrap.
The problem comes when these oils become clogged in the glands or become too thick to effectively spread out on the eye. This is called meibomian gland dysfunction.
These oils can also be broken down by an overgrowth of normal skin bacteria on the eyelids. These bacteria secrete chemicals into the tear film and destabilize the oil layer. This is called blepharitis.
Meibomian gland dysfunction and blepharitis actually account for the vast majority of dry eye!
Normally we blink enough times to prevent the tears from evaporating away too quickly. But when we are reading (such as reading this article), you blink less. With less blinking, the tears can evaporate from the eye exacerbating the dry eye.
The other cause of dry eye simply is that the eye doesn’t produce enough tears. Tears for the surface of the eye come from a gland near the eye called the lacrimal gland. If there aren’t enough tears on the surface of the eye, there isn’t as much buffer anymore to respond to changes in the environment. This type of dry eye is typically caused by certain medical conditions, procedures or medications.
In fact, you may be taking some over the counter medications right now that are contributing to dry eye. Lots of different medications will contribute to the eye drying out.
Other common medications that cause dry eye include medications used to treat high blood pressure, steroids, and medication used to treat depression and anxiety. But of course, you don’t want to stop these medications, you will want to just treat the dry eye instead.
So Why Is Dry Eye Bothersome?
The cornea is one of the most sensitive parts of the body. Because of this, the cornea doesn’t like being exposed to the environment. If the cornea doesn’t have it’s nice cushy coating, it will fire off neurons to you to tell you to do something about it! This causes:
- The feeling like there is something in the eye
- Burning
- Pain
- Watery eyes
- Eye redness
- Tired eyes
- Or a wide variety of other symptoms
Eventually, if the cornea is left out to dry for an extended period of time, the cells on the cornea start to become sick and cloudy and can cause you to lose vision. Fortunately this is reversible in almost all cases by treating the dry eye effectively.
As the eye dries out, inflammation starts to build up on the surface of the eye. This inflammation will cause the eyes to ache and in fact will lead to more dry eye. Thus, it is important to treat the dry eye effectively to prevent it from getting worse.
So How Is Dry Eye Treated?
Treating dry eye has a few basic principles. The most basic treatment is with artificial tears. These tears help replace our natural tears to coat and protect the surface of the eye. Using artificial tears is the best first step when treating dry eye.
Artificial Tears; Image courtesy of Amazon.com
But beyond artificial tears, there are many other treatments for dry eye. These treatments help improve the consistency of our tears and tear film, help us to improve the production of our tears and with some help prevent the tears from draining away as quickly. For the most optimal way to treat your eyes, it is always best to visit your eye doctor for a full evaluation.
Common treatments for dry eye:
- Eye lid scrubs to treat blepharitis
- Omega3 or Fish Oil supplementation to improve meibomian gland dysfunction
- Prescription eye drops such as Restasis, Xiidra, or Eysuvis
- Eyelid plugs to prevent tears from draining out of the eye
- Warm compresses or Lipiflow or iLux to improve the meibomian glands
And there are even more advanced treatments beyond this list. Again, visit your eye doctor for the optimal treatments for your eyes.
Summary
In short, while dry eye can be complex, the mechanisms behind it are relatively simple. Tears either evaporate too quickly or you just don’t produce enough; leaving you with an exposed and irritated cornea. This causes discomfort, burning, watery eyes and can even blur your vision. While there are many treatments for dry eye, using artificial tears is often the best first step to get the dry eye under control.
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