Understanding Dry Eye Syndrome & MGD

Understanding Meibomian Gland Disease (MGD)

For over 60 years, the term “Dry Eye” has been generally applied to a variety of uncomfortable eye surface problems, much in the same way the term back pain is generally used. The eye feels uncomfortable, but the cause is unknown. Dry eye symptoms have primarily been thought to be a direct result of the eye’s inability to produce the proper amount of natural tears, but we now know that is not the case for many dry eye sufferers.

Today, the leading cause of dry eye is known to be Meibomian Gland Disease (MGD) for over 86% of patients who present with symptoms, such as discomfort, redness, tearing, gritty or burning sensations and blurry vision. While MGD is chronic and progressive, if caught early, it can be effectively treated to stop the progression and maintain optimal eye health.

When Does MGD Occur?

MGD occurs when the meibomian glands, located in the eyelids, do not sufficiently produce and release the oils needed to protect and maintain a healthy tear film. This causes the watery layer in the tear film to evaporate. Thus, the problem for many dry eye patients is not inadequate tear production, as thought for so many years, but a lack of oil production that ensures the protective integrity of the tear film is maintained on a daily basis.

While more prevalent in older adults, MGD can occur at any age. In addition, improved detection methods have shown that MGD can occur in young adults and children, possibly because of the common use of digital display devices today. Excessive use of display technologies can lead to infrequent blinking, called “evaporative stress”.   Infrequent blinking creates a demand for more lubrication on the eye, stimulating more oil production from the meibomian glands.  Over time, this leads to thickening of the oil, blockage of the gland opening and shutdown of oil production in the gland.

MGD – A Growing Problem with Serious Consequences

The cause of MGD has been attributed to evaporative stress from infrequent blinking, which leads to thickening of the oil, blockage of the gland opening and shutdown of oil production in the gland over time. Various factors including the accumulation of debris that blocks the opening of the meibomian glands and infrequent or incomplete blinking can impact normal gland function. When MGD is present and left untreated over time, meibomian gland function is compromised. The gland content becomes stagnant and eventually, permanent gland loss occurs.

MGD is a chronic, progressive condition and should be detected and treated as early as possible.

Learn More About Treating MGD

Normal Gland Structure

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Gland Shortening and Loss

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Significant Gland Loss

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Severe Gland Loss

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Understanding Meibomian Gland Blockages

When the meibomian glands become blocked or their function is inhibited as a result of infrequent or incomplete blinking or other factors, they stop working. When the meibomian glands stop working, the oily layer protecting the tears becomes insufficient in thickness and quality.

When there is not enough oil on the top layer of the tear film, it causes evaporation of the aqueous (watery layer) and exposes our eyes to the elements, thus, resulting in chronic, uncomfortable dry eye symptoms. If the blockages are not cleared or the meibomian glands cease to function for long periods of time, structural damage and loss of the glands may result in long-term complications.

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A Clinical Perspective From Dr. Donald Korb and Dr. Caroline Blackie

BLOCKED GLANDS
BLOCKED GLANDS

aqueous-layer

Protective Water Layer

lipid-layer

Watery Layer is Protected by Oil

evaporation

Water Evaporating

MGD and the Tear Film

To understand MGD, it is important to first understand the tear film. The tear film is a complex structure of mucin, tears and oil that protects the surface of the eyes. When the tear film is compromised, it results in a variety of symptoms, most of which have been associated with dry eye and now MGD.

eye-diagram
Mucin Layer

The Sticky Foundation

The mucin (mucous) layer at the bottom of the tear film provides a “sticky” foundation and acts as a barrier to the eye surface.

Aqueous Layer

The Watery Center

The aqueous layer is the “juicy” center that is comprised of tears produced by the lacrimal glands.

Lipid Layer

The Oily Top

Finally, the top “oily” lipid layer of the tear film is made up of lipids or oils produced from the meibomian glands. When MGD is present, our glands do not consistently produce the oil necessary for a stable tear film and the aqueous layer will evaporate.

Mucin Layer

The Sticky Foundation

The mucin (mucous) layer at the bottom of the tear film provides a “sticky” foundation and acts as a barrier to the eye surface.

Aqueous Layer

The Watery Center

The aqueous layer is the “juicy” center that is comprised of tears produced by the lacrimal glands.

Lipid Layer

The Oily Top

Finally, the top “oily” lipid layer of the tear film is made up of lipids or oils produced from the meibomian glands. When MGD is present, our glands do not consistently produce the oil necessary for a stable tear film and the aqueous layer will evaporate.

eye-diagram

The Causes of MGD

Increasing use of computers and digital devices leads to blinking infrequently or incompletely, inhibiting meibomian gland function. The lid margin accumulates debris over time that can contribute to blockages in the meibomian glands. This is why many eye care professionals are now advocating lid care at an early age to ensure that the lid margin stays clean and the meibomian glands remain open.

There are also various factors that may possibly contribute to or promote the progression of MGD.  These include eye conditions such as contact lens wear; systemic conditions such as rosacea, androgen deficiency, menopause and Sjӧgrens syndrome; and medications such as antihistamines, retinoids, certain types of glaucoma medications, antidepressants, nizagara and postmenopausal hormone therapy. 12

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