Tuesday, January 31, 2017

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 (MGDis a chronicdiffuse 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 filmsymptoms of eye irritation, clinically apparent inflammationand 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 secretedA 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!

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