Dry eye disease is most commonly caused by a deficiency in one or more areas of the tear film. The tear film, or tears, are made up of three separate layers.
At the Alaska Dry Eye Center, we offer specialized diagnostic testing to determine which layer of the tears is causing your dry eye issues. This allows us to focus on treating your specific tear film deficiency.
Meibomian glands are modified oil glands that are arranged side by side in the eye lid. There are about 30 glands in the upper lid and 25 on the lower lid of each eye. These glands secrete an oil called Meibum. The force of your blink causes the meibum to be pushed onto the lash line. This oil initially protects the eye lids from breaking down from the moisture and creates a seal when the eyes are closed. As the oil interacts with the tears, it helps to spread the tears evenly across the eye, maintaining a consistent quality of vision. The oil also covers the tears, which keeps the tears from evaporating too quickly. A good analogy would be the puddle in the parking lot that doesn’t evaporate even on the hottest day of the year, because it is covered with motor oil from the cars that leak oil onto the lot.
Meibomian gland dysfunction can occur because of changes in the oil production as we age, as a result of poor diet, as a consequence of skin disorders such as rosacea or seborrheic dermatitis, or even because of poor eyelid hygiene. With Meibomian gland dysfunction, patients may not show any symptoms in the beginning, but eventually vision is affected because there is poor quality oil or too little oil in the tear film. This causes tear film instability, high tear osmolarity (too salty tears) and quick evaporation of the tears. Though dry eye itself may be caused by the excessive tear evaporation, the inflammation involved with dry eye irritation is actually worsened by the tears being too salty.
Its easy to dismiss the subtle signs of early MGD. Looking for oily lid margins, decreased oil in the tears, dilated meibomian glands, and thickened oils help to make the diagnosis. Even if patients show no symptoms, it’s not too early to learn about lid hygiene and meibomian gland disease. If a gland is blocked for too long, it begins to thicken and shrink or “drop out”, leaving behind a divot in the lash line. This can cause problems with the glands around it, as they try to fill in the space left behind and those glands can no longer push oil onto the correct part of the eye, which results in permanent changes in the tear film and leads to significant dry eye problems.
A happy patient who sees well is the goal of the doctors at the Alaska Dry Eye Center. In MGD patients, decreasing symptoms is important and the prevention of permanent damage that can affect the eye’s ability to maintain a balanced environment is paramount. Many effective treatments for MGD are available, so care can be tailored to each patient. Patients should recognize the signs and symptoms of meibomian gland dysfunction and understand that MGD is a chronic condition that requires a regular, if not daily, lid hygiene regimen. As with any chronic disease, continued care is a challenge. Luckily, most of the following at-home treatments are straightforward:
We also provide a variety of in-office MGD treatments! See our In-Office Treatment page for more information.
Evaporatiove dry eye is caused by MGD, and actually accounts for almost 80% of all Dry Eye Disease! Because the lipid layer of your tears is damaged or absent with MGD, your middle watery Aqueous layer is susceptible to damage. Your tears will dissipate faster, leaving you reaching for the eye drops more and more. Evaporative Dry Eye Disease can even cause excessive watering! Your body wants to keep your eyes lubricated, and will therefore send out more and more tears to keep them moisturized. People are often suprised that very watery eyes can be a sign of Dry Eye Disease!
Blepharitis is a chronic, inflammatory disease of the eyelids caused by an overgrowth of normal bacteria living along the lid and the base of the eyelashes. Anyone can get blepharitis at any age, but the prevalence increases with age, since as we get older, we make fewer natural antibodies in our tears.
This overgrowth of bacteria causes crusting along the eyelid and creates a sticky biofilm that harbors bacterial exotoxins. Since the eyelid margins are difficult to clean, this overgrowth of bacteria, scurf and biofilm can build up over many years. The sugary biofilm allows even more bacteria to flourish, not only causing a multitude of irritating symptoms, but eventually chronic inflammation, due to the inflammatory nature of exotoxins. The inflammation, in turn, adversely affects all of the structures in the eyelid, namely the tear glands.
The risk of blepharitis increases as a patient ages. A study by Walter Reed Hospital determined that incidences of blepharitis in the U.S. steadily increase from 3% of 18-20 year olds to a staggering 71% of those over 65. That equates to more than 40 million individuals in the 65+ age group with the total number of patients with blepharitis in the U.S. alone is over 82 million people.
According to a study conducted in 2009, “most ophthalmologists and optometrists report that blepharitis is commonly seen in their clinical practice in 37% to 47% of their patients, respectively, and it is widely agreed that the meibomian gland dysfunction caused by blepharitis is the most common cause of evaporative dry eye disease.”
Meibomianitis, a form of blepharitis, is the most common form of lid margin disease; nearly 40% of routine eye care patients and 50% of contact lens wearers are affected. Meibomianitis may cause or increase dry eye-like symptoms. Dryness, itching, stickiness, sandy/gritty feelings, burning, watering, light sensitivity, and fluctuating blurry vision are frequently seen in cases of meibomianitis. Meibomianitis can exist alone or with other forms of blepharitis or seborrheic dermatitis.
While about 80% of Dry Eye Disease falls under the Evaporative Dry Eye category, the other 20% is made up of Aqueous Deficiency and Inflammatory Dry Eye.
Aqueous Deficiency occurs when the lacrimal gland, located above the eye, is unable to produce enough of the aqueous part of the tears. The aqueous layer is the watery layer and is what most people think of when they think of tears. There are a variety of reasons for this to occur, such as age, hormonal changes, and environmental factors. It can also be affected by inflammation and go hand in hand with Inflammatory Dry Eye.
Inflammatory Dry Eye affects all layers of the tear film. As said above, inflammation can cause the lacrimal glands to decrease aqueous production, but it can also cause irritation to the meibomian glands, decreasing oil production. Inflammation can also have an affect on the mucin layer and prevent the tears from spreading evenly across the eyes. Inflammatory dry eye is typically caused by systemic diseases, such as Lupus or Sjrogen's, or even arthritis.