meibomian gland dysfunction

image: All About Vision

What are meibomian glands?

Meibomian glands are sebacous (oil) glands located in the upper and lower eyelids. There are more in the upper lid than the lower lid, and they are also larger in the upper lid (1). The glands sit vertically in the eyelids, and their openings are right behind the lash line. The job of the meibomian glands is to make and secrete oil. These secretions make up one of the 3 layers of the tear film, the lipid layer. Blinking helps spread the secretions on the surface of the eye, keeping the tear film stable and preventing it from evaporating too quickly. The function of the glands is regulated by hormones such as androgens, estrogens, and progestins. 

A visibly capped meibomian gland

What is MGD?

Meibomian gland dysfunction, or MGD, is not the most clearly defined condition.  Here's the technical definition:

"Meibomian gland dysfunction (MGD) is a chronic, diffuse abnormality of the meibomian glands,commonly characterized by terminal duct obstruction and/or qualitative/quantitative changes in the glandular secretion. It may result in alteration of the tear film, symptoms of eye irritation, clinically apparent inflammation, and ocular surface disease." (2)  

Translation? MGD is when the meibomian glands don't work right. The dysfunction is typically either a result of a blockage in the gland or an abnormality in the oil being secreted. A blockage may present as a clear or opaque dome at the opening of the glands (see photo above). MGD can also involve changes in the quality and quantity of secretions. When pressure is applied to normal glands, they should secret a small amount of clear oil. In the case of MGD, the secretion is thicker and more yellow-white in color. I liken it to when you leave a tube of toothpaste open for a while, and you get some crusty, solidified gunk at the opening that you have to squeeze out to get to the usable toothpaste. 

What are the signs and symptoms of MGD?

Some common symptoms include dryness, a sandy/gritty feeling, a burning sensation, eye and lid irritation, contact lens intolerance, eyelids sticking together in the morning, and even blurry vision. These symptoms are also symptoms of similar but distinct conditions, so a thorough examination of the eyelids, tear film, and front surface of the eye by an eye doctor is warranted to help identify what the source of the issue is. 

Common associated signs of MGD are thickened eyelid margins, frothy tears, and a low tear break-up time (the time it takes for the tear film to break up due to evaporation). In fact, dysfunction of the meibomian glands is one of the main causes of evaporative dry eye disease. Not only does it cause dryness, but insufficient lipids may cause increased bacterial growth on the lid margins, which can cause a number of secondary lid issues (2).

What is MGD associated with?

• Age: MGD increases in prevalence with age (3).
• Contact lens wear: Studies suggest a decrease in functional meibomian glands with contact lens wear (4, 5).
• Ethnicity: MGD appears to have a much higher prevalence among Asian populations (2). 
• Systemic factors: menopause, rosacea, Sjogren's syndrome, etc. 

How is it treated?

There are various treatment options available, depending on the severity and associated symptoms/signs.  Here is a list of treatments I typically recommend for MGD, going from least complex (for milder cases) to most complex. 

1) BLINK! Blinking stimulates the secretion of meibum, and helps spread it across the surface of the eye. Studies show you blink less when reading, and you blink 60% less when at the computer (6).  So take frequent breaks, and make a conscious effort to blink completely during those breaks.

2) Warm compresses with lid massage. Taking a page out of a colleague's book, it's the flossing of the eye world- it's something you SHOULD do daily to prevent disease, but not a lot of people do it religiously. 

• Use a warm washcloth (or a boiled egg or warmed dry rice wrapped in a cloth- somethng that stays warms for a few minutes) and rest it over your eyelids with your eyes closed. Do so for at least 5-10 minutes. Gently massage your eyelids, rolling your fingers vertically down your upper lid and up your lower lid (towards your lashes). This helps get the oils flowing normally, and also helps remove any solidified gunk at the opening of the glands.
• I recommend doing this twice daily when symptoms are present, or when MGD is first diagnosed. Beyond that, once daily is great for maintenance.
• Follow up with a lid cleanser, gently scrubbing along the lash line to remove debris, makeup, and bacteria that may clog or infect the oil glands. A cleanser containing diluted tea tree oil is particularly beneficial if Demodex is present. 

Lipiflow is an in-office procedure that accomplishes the same thing, though more effectively.  The device heats the internal surface of the lids and simultaneously applies pressure to the external lid to express the glands, all in about 12 minutes. 

3) Omega-3 fatty acids. Omega-3s help improve the quality of the oil produced by the meibomian glands, and they have anti-inflammatory effects. A great source of omega-3s is fatty fish, like salmon and tuna. Another option is fish or flax seed oil supplements. It's always a good idea to consult with your doctor before starting any supplement.

4) Artificial tears can also help beef up the contents of the tear film.  Lipid-based artificial tears are best in the case of MGD because they help replenish the lipid layer of the tear film, and not just the aqueous layer. Some lipid-based drops: Systane Balance, Soothe XP, Retaine MGD, and Refresh Optive Advanced. 

5) Prescription medications.  Depending on the other presenting conditions, some patients with MGD may require the use of antibiotics. Topical azithromycin or low-dose, long-term use of oral doxycycline are thought to alter the eyelid bacteria and also provide anti-inflammatory effects (7, 8). Still others with severe MGD may need to have the inflammation controlled through the short-term use of a topical steroid drop or the long-term use of a dry-eye drop. 

CliffsNotes: MGD can alter the makeup of the tear film, leading to eye irritation, inflammation, and dry eye. So see your eye doctor STAT to nip it in the bud!

Additional Resources:

• All About Vision

Demodex

What is Demodex?
Demodex is an 8-legged, microscopic mite. Two species live on humans: Demodex folliculorum, which are found in the eyelash follicles, and Demodex brevis, which are found in the sebaceous (sweat) and meibomian (oil) glands. These mites live primarily on the face and feed on skin cells and oil in the follicles and glands. They avoid sunlight and live for about 2 to 3 weeks. How common are they? Fairly common in adults (studies report they are found on the skin of 20-80% of adults- that's a pretty wide range and not a super helpful stat...), and nearly 100% of elderly people have the mites on their skin (1). Studies have shown that the prevalence of Demodex increases with age, and Demodex mites are present in higher numbers in those with rosacea, compromised immune systems, and possibly contact lens wearers (2, 3).

Two D. folliculorum on a plucked eyelash (A) and one hanging solo (B)
image: JKMS

Fun (or disgusting) fact: Demodex mites have no anus. Their waste is stored in the gut and expelled when they die, which may cause additional inflammatory response. Shout-out to one of my patients who shared that fact with me. #mypatientsaresmarterthanme

Demodex being teased out of the follicle (arrow) via lash rotation
image: Optometry and Vision Science

What problems can Demodex cause?
Many people have Demodex mites on their skin and have no symptoms or complications. However, Demodex overpopulation (demodicidosis) has been linked to (not necessarily causative of) skin conditions such as blepharitis, rosacea and perioral dermatitis, as well as meibomian gland dysfunction, dry eye, recurrent chalazion, and ocular surface inflammation (4, 5).

Demodex mites can cause problems by clogging hair follicles and sweat ducts, causing abnormal thickening and growth of the epithelial cells at the lid margin. Further, the exoskeleton and waste of the mites can cause an inflammatory response (6, 7). Overpopulation of Demodex mites has been linked to an increase in the presence of certain cell-signaling proteins (cytokines, specifically interleukins) in the tears, which can cause an inflammatory or immunological response (8).

The presence of cylindrical dandruff or "waxy sleeves" around the base of the eyelashes is a very good indicator of demodicidosis. Symptoms may include itching and redness of the lid margin, loss of lashes or misdirected lashes, as well as burning or irritation.

Cylindrical flakes that are highly suggestive of demodex
image: Review of Optometry

How do you get rid of the little buggers?
Frequent scrubbing of the lids with diluted tea tree oil (TTO) was found to be the most effective way to eradicate Demodex and improve patient symptoms (9). The TTO has ingredients (namely, terpinen-4-ol) that kill mites and ticks while also luring the mites out of the hair follicle before they mate (10). There are also lid wipes, scrubs and shampoos containing various concentrations of TTO that can be used for at-home treatment and long-term maintenance. It is best to keep the concentration of TTO at or below 50%; any higher than that may be too irritating (11). Your eye doctor may choose to add an antibiotic and/or steroid ointment or drop to the treatment as indicated, depending on what other symptoms and signs are present.


CliffsNotes: If you suffer from dry, itchy, irritated, red, and/or crusty eyelids, have your optometrist take a look. You MITE (see what I did there?) have a Demodex party going on in your eyelashes. 


Additional Recommended Resources:

• National Geographic: Demodex