What Is Dry Eye Disease?

The Tear Film

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. 

  1. Mucin. This layer is the inner layer and is responsible for protecting the most sensitive part of your eye, the cornea. It allows the other layers of the tears to spread evenly across the surface of your eyes.
  2. Aqueous. This is the middle, watery layer and is the main component of your tears. It is produced by the lacrimal glands above your eyelids. A deficiency in this layer of your tears can be caused by a variety of issues, from gland dysfunction to dehydration.
  3. Lipid. This is the outer, final layer of the tear film. This layer is made of oily lipids, created by the Meibomian Glands, and are designed to keep your tears from evaporating too quickly. A deficiency in this layer is caused by Meibomian Gland Dysfunction and is one of the leading causes of dry eye disease.

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. 

The Signs of Dry Eye:

  • Red Eyes
  • Burning
  • Itching
  • Foreign Body Sensation
  • Sandy/Gritty Feeling
  • Light Sensitivity
  • Watery Eyes
  • Pain/Soreness in or Around the Eyes
  • Red/Irritated Eyelids
  • Tired Eyes
  • Contact Lens Discomfort
  • Dry Mouth


The Meibomian Glands

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 (MGD)

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.

Early Signs of MGD

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. 

Care for MGD Patients

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: 

  • Warm Compresses:  Heating the lids significantly increases meibomian oil production and liquidity. Heat should be applied with the warm compress for 10 minutes, this warms the oils, allowing it to flow more freely, and helps soften lash line debris and buildup. We offer an eye compress that microwaves for 20 seconds and is to be used daily.
  • Lid Scrubs: Lid scrubs help to remove excess oils, bacteria, and debris, as well as to stimulate the meibomian glands. Baby shampoo or mild soap have historically been recommended to patients with blepharitis, however, some patient’s eyes are sensitive and can become swollen because of the soap. OcuSoft and TeaTree foaming eye wash are bactericidal products, meaning they kill bacteria. These products can be less irritating to the eyes than shampoo or soap. Lid scrubs may be prescribed at different steps within the lid hygiene regimen. In patients with anterior blepharitis, lid scrubs should be performed before a lid massage so that the lashes are cleared of bacteria and debris. 
  • Omega-3 Fatty Acid: These are found in fish oils and flaxseed and are commonly recommended to patients with dry eye, meibomian gland dysfunction or meibomianitis (see the next section for more info about meibomianitis!). They are polyunsaturated fats and result in the meibomian glands producing a thinner oil that flows better. Omega 3 fatty acids also have anti-inflammatory effects.
  • Prescirption and Non-Prescription Drops: Eye drops are designed for a variety of purposes. Some drops will target inflammation and promote tear production while others can be used as a temporary replacement for the oil layer of your tears. 

We also provide a variety of in-office MGD treatments! See our In-Office Treatment page for more information.

The Effects of MGD


Evaporative Dry Eye Disease

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. 

  • Primary Meibomianitis:  Also known as Obstructive MGD, primary meibomianitis is a generalized dysfunction of the meibomian glands. It is commonly associated with acne and seborrheic dermatitis. The lid margin typically appears abnormal, with the meibomian glands dilating, or widening, and blocked with oils that are sluggish or thick. This can cause the eyelids to look red or swollen and can cause the whites of your eyes to appear red or pink. 
  • Anterior Blepharitis:  This is a bacterial infection of the lash line that can lead to secondary infection and inflammation of the meibomian glands. In addition to the typical signs of blepharitis, there may be plugged or inflamed meibomian glands and dry scales at the base of the eye lashes. It is unclear if the bacteria cause the oil from the glands to thicken or if the bacteria simply worsen the problem by causing inflammation. But, it is known that certain bacteria can release waste that irritate the eyes and cause an unstable tear film. 
  • Seborrhic Blepharitis: Patients with seborrheic dermatitis (a skin condition that affects the oil glands of the scalp, face, and eyebrows) often also have scurf, which are greasy flakes on the lashes, and have inflamed or infected lash lines. The condition is known as seborrheic blepharitis. These patients may simply have an increase in meibomian gland secretion. Along with the greasy scales seen in the lashes, excess meibomian oil is usually evident on the lash line and in the tears. The meibomian glands are dilated and full of oils that can be easily pushed out. Frequently, soapy-looking bubbles are seen along the bottom lash line. This bubbling occurs when excess oil reacts with a protein in the tears. Patients with this condition frequently complain of burning when waking up. The condition is similar to getting soap in your eyes. Inflammation is usually minor in cases of seborrheic blepharitis, so patients may not have obvious symptoms. The localized inflammation that results from the condition can lead to permanent thickening and scarring of the meibomian glands. Due to a lack of oil in the tears, these patients typically have an increased tear evaporation. 


Aqueous Deficiency & Inflammatory Dry Eye

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.