Meibomian Gland Dysfunction - Causes, Symptoms, and Management

Introduction

The primary function of the eyelid and tears is to provide a moist cavity and protect the eyes from dust and injury. Tear film covers and lubricates the ocular surface of the eye, maintains a smooth surface for light refraction, and preserves the health of the cornea and conjunctiva. The tear film comprises three layers: the watery layer lubricates and maintains the eyes' moisture, the oil layer prevents evaporation of the watery layer, and the mucus layer spreads the tears to include the entire surface of the eyes. Problems in these layers can cause irritation, dryness, or blurred vision.

What Is Meibomian Gland Dysfunction?

Meibomian gland is a type of sebaceous gland (oil gland) located along the edge of the eyelids. These glands secrete meibum (an oily substance), which is delivered to the eye surface and coats the aqueous layer, providing stability to the tear and protecting against microbial agents. The meibomian gland is called so because it was first described by a German physician, Heinrich Meibom. There are approximately 25 to 40 meibomian glands in the upper eyelid and around 20 to 30 glands in the lower eyelid.

Meibomian gland dysfunction is a broad term that describes a group of disorders associated with the abnormalities of the meibomian glands. Any disruption in the functioning of the meibomian glands impacts the quality and quantity of meibum secretion, which alters the tear film composition. It is an underdiagnosed and undertreated eye disease as it is asymptomatic in many people. The prevalence of meibomian gland dysfunction increases with age and is usually seen more in males than females.

What Causes Meibomian Gland Dysfunction?

Meibomian gland dysfunction can occur when there is a blockage in the glands or an alteration in the quality of oil secreted by the gland. Some of the factors that can cause meibomian gland dysfunction include:

• Environmental Stress: It is an important factor contributing to meibomian gland dysfunction, as stress alters the meibum protein or lipid ratio, causes the depletion of cells that produce meibum, and thus results in hyposecretion. Additionally, if the protein or lipid ratio increases, it can increase the production and viscosity of the meibum, hurting the tear film stability.

• Aging: Age is a main risk factor for meibomian gland dysfunction. Due to aging, the meibomian gland cells and lipid production decrease, thus altering the meibum composition.

• Medications: Estrogen or hormone replacement therapy, medicines that decrease androgen levels, retinoids, glaucoma treatment, antidepressant drugs, antihistamines, and acne medications are known to be associated with MGD.

• Medical Conditions: Meibomian gland dysfunction can also occur due to bacterial infections, allergic conjunctivitis, increased cholesterol or triglyceride levels, and systemic disorders such as Stevens-Johnson syndrome, rheumatoid arthritis, rosacea, psoriasis, Sjogren’s syndrome, polycystic ovary syndrome, etc.

• Risk Factors: People who wear contact lenses or eye makeup are more likely to get MGD. Ethnicity is also a factor to be considered, as studies have shown that Asians are three times more prone to meibomian gland dysfunction than Europeans.

What Are the Symptoms of Meibomian Gland Dysfunction?

Symptoms of meibomian gland dysfunction vary among individuals; some may experience only mild discomfort, while for others, it can be harsher. These include;

• Dry eyes.

• Blurred vision.

• Itchy eyelids.

• Red and swollen eyelids.

• Sensitivity to light.

• Watery eyes.

• Burning sensation in the eyes.

• Flaking of the skin around the eyes.

• Excessive blinking.

• Sticky or crusty eyelashes after waking up.

• Abnormal growth of eyelashes.

What Are the Complications of Meibomian Gland Dysfunction?

Meibomian gland dysfunction is often a mild disease and hence overlooked in the initial stages. However, it must be treated as early as possible as it can lead to complications such as blepharitis (inflammation of the eyelids), dry eye syndrome, or evaporative dry eyes. If left untreated, it can affect the tear film quality, cause redness of eyelid margins, increase the risk of bacterial eye infections and inflammation (swelling), or even lead to corneal damage. Another complication of MGD can be Demodex (tiny parasitic mites) infestation of the eyelids. Care must be taken for MGD patients planning to undergo cataract surgery or any other intraocular procedures, as they are at a high risk of developing persistent dry eyes, infections, meibomian gland dropouts, or endophthalmitis (inflammation of the intraocular cavity).

How Is Meibomian Gland Dysfunction Diagnosed?

A comprehensive eye examination diagnoses meibomian gland dysfunction. The eyes are detailed to check for associated signs, such as dry eyes or damage to the ocular surface. An eye specialist may prepare a validated questionnaire to identify the symptoms and determine the diagnosis.

• Pressure Test: The doctor applies mild pressure on the eyelid to observe the secretions' quality, quantity, and stability.

• Meibography: It is a non-invasive test in which images of the meibomian glands are taken using laser imaging, infrared, or optical coherence tomography (OCT). It helps to evaluate the morphology of the meibomian glands and determine their functioning efficiency.

• Tear Breakup Time Test (TBUT): This procedure is common to determine tear film stability. It involves placing a drop of a dye in front of the eyes to be absorbed by the tear film. The doctor then examines the eyes with a blue light, which helps the tears glow. If the tear film has less stability, it can be observed in the test, as the tears will quickly break apart.

• Schirmer Test: This test determines tear production. The doctor places the test strips on the right and left eyes and pulls the lower eyelid to put the bent portion of the strip between the eye and lower eyelid. After a few minutes, the strip is removed and tested for moisture content.

How Is Meibomian Gland Dysfunction Managed?

There are different treatments to manage meibomian gland dysfunction depending on the severity and overall health of the patient. Some of the treatment options include:

• Massage: The eyelid margins and the area above the eyelashes can be massaged by applying mild pressure with the fingertips. The finger must be rolled upwards on the lower eyelid while looking up, and then the finger must be rolled downwards on the upper eyelid while down. It must be done gently and in moderation, as it may cause pain or irritation.

• Warm Compress: Placing a clean, warm, wet cloth or a towel over the eyelids for a few minutes can help increase oil production and soften eyelash debris. Eye masks or eye pads with gel are also available, which can be helpful.

• Screentime: Reducing screen time, taking frequent breaks between sessions, and blinking the eyes can help prevent dry eyes. Protective eyewear can also be beneficial when watching screens or going out in a windy environment.

• Diet: Foods rich in Omega-3 fatty acids, such as fatty fish, flax seeds, chia seeds, and nuts, can be included in the diet, as they improve the consistency and quality of the oil produced by the meibomian glands.

• Eyelid Scrubs: Scrubbing the eyelids and eyelashes with a Q-tip, a clean, warm cloth, or fingertips, and washing with mild soap and water removes dust, debris, and bacteria that block the gland openings.

• Medications: Eye specialists usually prescribe lubricating eye drops, ointments, antibiotics, and anti-inflammatory drugs such as steroids or Cyclosporine, depending on the patient's condition. New treatment modalities include intense pulsed light treatment (series of light pulses that stimulate the meibomian glands), tear care (heat patches that unclog the glands), Blephex (a hand-held device that exfoliates the eyelid margins to eliminate the bacterial debris), immune-based eye drops (to reduce inflammation, bacterial overgrowth, and improve tear flow), and surgery.

Conclusion

Meibomian gland dysfunction is an umbrella term referring to the functional abnormalities of the meibomian glands. It is a commonly prevalent condition but is under-recognized and complex to diagnose. It is mainly associated with dryness of the eyes, blurred vision, an itching or burning sensation, and crusty eyelashes. Certain home remedies and medications can effectively manage it. However, it is recommended to consult an eye care specialist as early as possible to avoid ocular discomfort and prevent complications.