What is Evaporative Dry Eye Disease?
By far the most common type of dry eye disease is evaporative dry eye. Approximately 83% of all dry eye patients have an evaporate component to their dry eye. The most obvious symptom of evaporative dry eye is blurry vision that gets better after you blink. Most patients also have irritated, red, dry eyes while others may actually have the symptom of watery eyes. This means that you may be producing plenty of tears, but because the quality of the tears are low, they evaporate way too fast. This negatively affects your eyes in a few ways. First, your visual clarity will likely suffer. The first part of your eye that an image hits is your tear film, and if your tear film is disrupted, you will have intermittent blurry vision no matter how perfect your glasses or contact lens prescription is. If you find that your vision comes in and out of focus when driving, on the computer, or any other visually demanding time, there is a high likelihood that you are suffering from evaporative dry eye. Second, evaporative dry eye makes your eyes feel irritated, dry, and appear red. Your tear film is not adequately protecting the cornea, which has one of the highest concentrations of nerve endings in the body. Finally, evaporative dry eye can lead to the perplexing symptom of watery eyes when you actually have dry eyes. If the tear film evaporates too fast, your eyes feel dry, and they send a signal to the brain, saying “we are dry, we need more tears!!” The brain responds by dumping more tears on your eyes, causing your eyes to water. However, these tears are still of poor quality, evaporating too fast, and continuing the signal cascade to the brain. If you find that you are constantly wiping tears away from your eyes, except when watching a sad movie, you are likely suffering from evaporative dry eye. We can test this directly by focusing a microscopic video camera on your tear film, and record how long it takes for your tear film to evaporate between blinks (Figure 1: NIKBUT photo)
Ready for some tear film science? Good, me too! To simplify, there are 2 main layers in your tear film, an oil layer and a water layer. The oil layer forms a protective outer barrier for the water layer, much like looking at an oil slick on a puddle on a rainy day. This protective oil layers keeps the tears from evaporating too fast. We have oil glands called Meibomian glands that are located in our upper and lower eyelids, and their openings are right on your water line, the 1-2mm area on your eyelid between your eyelashes and your eyeball. During our routine Dry Eye Exam at Peak Eyecare, we image these glands using an infrared camera. We then compare your glands to a normative database, where we look for early signs of gland atrophy and adjust our treatment recommendations accordingly. In a healthy eye, these meibomian glands produce an olive oil-like substance called Meibum during every blink, and this meibum forms the protective oil layer on your tear film. In Dry Eye Disease, these oil glands are surrounded by inflammation, which is seen as small little blood vessels called telangiectasia that we can image in our office (see figure 2 of one of our patient’s lids). This inflammation can lead to clogging of the meibomian glands, which changes the meibum from an olive oil consistency to a toothpaste-like consistency. This thick clog prevents the meibomian glands from releasing the protective, essential oil that the tear film needs for stability. Further, if these meibomian glands remain clogged for a long period of time, they can start to atrophy (die off), and once they atrophy, there is no way to regenerate them. Our goal is to never let these glands die off, because if they do, your dry eye symptoms will get drastically worse, and there is little that we can do at that point.
Figure 1: NIKBUT
Figure 2: Eyelid
Evaporative Dry Eye Treatments
Once your doctor has identified evaporative dry eye, what can be done? The goal of treatment for evaporative dry is centered around restoring proper function of your meibomian glands. In most cases of evaporative dry eye, the oil in the meibomian glands, called the meibum, becomes thick and white, having a toothpaste-like consistency. If this occurs, little to no meibum can be expressed from the glands when you blink, making the tear film unstable and evaporate too fast.
At-Home Treatment for Evaporative Dry Eye
My first line of treatment for evaporative dry eye is an at-home treatment that involves the application of a warm compress for 10 minutes every day. This is best done with an eye-specific mask that you put in the microwave for 20-30 seconds, then with your eyes softly closed, place the mask over your eyes. The heat from the mask warms the thick meibum above its melting point, allowing it to flow much more easily from your meibomian glands, thus keeping your tears more stable. An analogy would be butter on a pan. If we apply heat to the pan, we can melt the thick butter until it becomes more liquid. A few of my patients have asked what they can do if they do not have a microwave, and the workaround is using a hot washcloth. However, the washcloth loses its heat after only a few minutes, so if you chose to do this route, you need to keep a pot of warm water next to you in order to keep on reheating the cloth throughout the 10 min. A mask like a Bruder mask is much more effective.
In-Office Treatment of Evaporative Dry Eye
For patients with very thick meibum, so thick that none is getting onto the tear film and the Non-Invasive Tear Break Up Time (NITBUT), as measured with the Oculus K5M seen in Figure 2, is less than 7 seconds, warm compresses at home is likely not enough. At Peak Eyecare, we offer an in-office treatment called Thermal Expression. In this procedure, a pair of specialty designed googles are placed over your closed eyes for 10 min to safely heat your meibomian glands more than you can with just the mask at home. Patients almost always comment on how relaxing it feels during these 10 minutes. After that is finished, I will physically express your glands with a special tool with the help of my microscope. My goal is to squeeze out the toothpaste-like meibum that is blocking the glands until the meibum runs clear like olive oil. We do this procedure twice, separated by 2-3 weeks. It is imperative that you continue to use the warm compress at home during this time to keep the newly cleared glands from clogging up again. Patients report that they notice a big improvement in their symptoms and are less reliant on artificial tears after.
However, no matter how much we do to improve the consistency of the meibum, if we do not also address the inflammation surrounding the openings of these glands, they will continue to clog. At Peak Eyecare, we take high-magnification images of your lid margin to look for telangiectasia, which are tiny blood vessels on the surface of your skin, also known as “spider vessels” (see figure 3). If we see telangiectasia, we have proof that you have excessive inflammation around your meibomian gland openings, and we will be constantly battling the reclogging of your meibomian glands. Our first line of treatment for this is HydroEye Supplements, which is a combination of Omega 3 (Fish Oil) and GLA (an Omega 6 from Black Currant Seed Oil). Working together, these supplements decrease inflammation around the meibomian glands and help your lids produce a healthier meibum. Most patients notice an improvement after 30 days of taking the supplements.
What special equipment can treat evaporative dry eye?
By far the best treatment for inflammation and meibomian gland dysfunction is Intense Pulsed Light therapy, or IPL. This 4 part treatment provides the biggest improvement in the health of your meibomian glands, and the longest lasting relief of dry eye symptoms compared to any other treatment develops thus far. Please read the page, IPL for Dry Eye Disease, for an in-depth look at this game-changing technology.