Last Updated on September 1, 2020
Meibomian gland dysfunction (MGD) is a chronic condition in which the meibomian glands present in the eyes do not secrete enough oil or secrete oil of poor quality.
The condition is also known as “meibomianitis.”
It occurs due to blockage or other abnormality of the meibomian glands so they don’t secrete enough oil into the tears. The absence of the oily layer from the tear film causes the tears to evaporate very rapidly. This results in dry eye syndrome.
Read more about Dry Eye: Causes, Symptoms, Prevention, and Treatment
It is an underdiagnosed disease. Also in many cases, the disease is asymptomatic.
It is more common in Asians as compared to Caucasians.
The incidence of the disease increases with age. About 70 % of Americans more than 60 years of age are estimated to be suffering from MGD.
The incidence is higher in males as compared to females.
What Are Meibomian Glands?
Meibomian glands are sebaceous glands present in the eyelids. These glands secrete oils or lipids or meibum that form the outer layer of the tear film.
They are named after Heinrich Meibom, the German doctor who first described them in 1666.
The tear film is composed of three layers.
- An oily or lipid layer or meibum
- A watery or aqueous layer
- A mucous layer
The oily or lipid layer or meibum is the outermost layer of the tear film. It is responsible for providing stability to the tear film. It helps to make the tear surface smooth and prevents tears from drying up too fast.
The watery or aqueous layer is the middle layer of the tear film. This layer cleans the eye and washes away any foreign particle that enters the eye. It is produced by the lacrimal glands present near the eyelids.
The mucus layer is the innermost layer of the tear film. It helps to spread the watery layer over the surface of the eye. In the absence of mucus, tears will not be able to stick to the eye. It is produced in the conjunctiva.
There are about 25 to 40 meibomian glands in the upper eyelid and about 20-30 in the lower eyelid. Each gland is composed of clusters of around 10-15 secretory acini. These acini drain into small ductules which together drain into a common central duct.
Each gland opens into the lid margin and secretes lipids to form tear film.
The contraction of the orbicularis muscle which occurs during blinking along with the contraction of Riolan muscle which is present at the terminal part of the meibomian ductal system results in the production of a mechanical force that facilitates the secretion of oil or meibum.
Meibum consists of around 100 major individual complex mixture of lipids, several proteins, and electrolytes.
Increasing age, dietary deficiencies, deficiency of sex hormones, excess usage of antibiotics, and dysfunction of meibomian glands can cause alteration in the composition of lipids and proteins in the meibum. This can ultimately lead to altered tear film stability and function.
Risk Factors For Meibomian Gland Dysfunction
Age: people above the age of 50 years are more likely to have meibomian gland dysfunction
Deficiency of sex hormones especially androgens
Ethnicity: It is more common in certain Asian populations like Thailand, Japan, and China. In comparison, the incidence is less in Caucasians.
Regular use of eye make-up and eyeliner can cause blockage of the openings of meibomian glands. More so over, if the eyelids are not thoroughly cleaned before going to sleep.
Systemic conditions such as Sjogren’s syndrome (SS), Stevens-Johnson Syndrome (SJS), psoriasis, atopy, polycystic ovary syndrome (PCOS), and hypertension.
Eye conditions such as aniridia, chronic blepharitis, wearing of contact lens, trachoma, Demodex folliculorum infection can also result in Meibomian gland dysfunction.
The use of certain medicines may also contribute to MGD. These include:
- Antibiotics
- Isotretinoin for acne
- Antihistamines
- Antidepressants
- Hormone replacement therapy
Read more about Sjogren’s Syndrome -Features, Diagnosis,careTips, and Treatment
Clinical Features
Signs and symptoms of meibomian gland dysfunction are similar to dry eye. These include:
- A scratchy feeling, like a sensation of having something in the eye
- Stinging or burning sensation in the eyes
- Stringy mucus in or around the eyes
- Redness of eyes
- Sensitivity to light
- Eye fatigue
- Blurred vision
- Watery eyes, which is the body’s response to the irritation of dry eyes
- Difficulty wearing contact lenses
- Difficulty with nighttime driving
Diagnosis
No single test can confirm the diagnosis of MGD. A detailed patient’s history to know about the signs and symptoms, general health problems, medications, etc is taken.
Clinical examination of the eye, tests to detect the degree of eye dryness, tests to measure the quality of the meibum, and how fast the tear film loses its stability help to arrive at the diagnosis.
Eye examination
Detailed eye and eyelid examination by an opthalmologist is carried out to inspect the meibomian gland openings. Applying pressure to the eyelids squeezes out the clogged oil and indicates the presence of meibomian gland obstruction.
Schirmer’s test
It measures the degree of dryness of the eyes. A small piece of filter paper is kept inside the lower eyelid for five minutes to measure the production of tears. The wetness is then measured with a ruler. Reduced wet area indicates dry eye.
Tear breakup time (TBUT) test
In this test, a small amount of dye is applied to the tear film on the front surface of the eye. The eye is then examined with a cobalt blue light that causes the tears to glow. This test can determine how quickly the tear film loses its stability or breaks up thereby indicating a deficiency of oil within the tear film.
Complications
MGD is the most common cause of dry eyes and can lead to complications related to dry eyes.
Blepharitis
MGD can cause inflammation of the eyelids which is called blepharitis.
Eye infections
The dryness of the eyes resulting from MGD can result in an increased risk of eye infections.
Damage to the surface of the eyes
Severe dry eyes, if not treated may cause abrasion of the corneal surface and corneal ulcers leading to defects in vision.
Difficulty in performing routine activities
Meibomian gland dysfunction and resultant dry eyes can cause an uncomfortable sensation and may cause difficulties in performing day to day activities, such as reading, watching television, etc. This may lead to decreased quality of life, headaches, or even depression.
Treatment
The aim of treatment is to increase the flow of meibomian gland secretions so that the resulting tear film is stable and does not evaporate quickly.
Warm compresses and massage
The traditional treatment involves applying warm compresses to the eyelids and then massaging the eyelids. This helps to soften and express the thickened oil which is clogging the openings of meibomian glands.
Meibomian gland probing
Anesthetic drops are instilled in the eye to numb the eye. A hand-held instrument is used to probe, open, and dilate the openings of the meibomian glands. Although this procedure is quite effective, it is slightly uncomfortable.
Emulsion eye drops containing lipids
Oil-in-water emulsion drops containing lipids help to increase the lipid layer thickness in the tear film. They improve tear film stability and tear spreading and also help to reduce tear evaporation.
LipiFlow® thermal pulsation system
This treatment involves the simultaneous application of heat and pressure to the eyelids. The heat is applied directly to the inner surface of eyelids and helps to melt the waxy deposits in the meibomian glands. The application of pulsed pressure opens and expresses the contents of the glands. This procedure causes minimal discomfort to the patient. Also, the heat or pressure applied to the eyelids is not transferred directly to the eyeball.
A single session of LipiFlow® treatment usually lasts for 12 minutes. In contrast, conventional warm compress therapy usually takes more time to complete.
LipiFlow® may result in certain side-effects like eyelid pain, conjunctival vascular injection, ocular burning, etc. Most of these, however, get resolved within a month without treatment.
Artificial tears
They provide lubrication to the eyes and hence result in symptomatic relief from dry eyes. They are available in the form of eye drops. gels or ointments and can be obtained as over the counter drugs meaning without a prescription.
Antibacterial eye drops
These may be used to resolve meibomian gland dysfunction as well as to treat infections.
Cyclosporine eye drops (Restasis)
Cyclosporine is an immune modulator that helps to modify the body’s immune response. Besides lubrication, they reduce the inflammation associated with dry eyes and help the body to produce more natural tears.
Steroid eye drops
These may also be prescribed for a brief period to reduce the underlying inflammation associated with meibomian gland dysfunction. However, they should not be used for a prolonged period of time as they can cause serious side-effects like high eye pressure or cataracts.
Omega-3 supplements
Dietary supplementation with omega-3 fatty acids may be used as an adjunct treatment for MGD. These supplements help to suppress inflammation, reduce the risk of accumulation of waxy material within the meibomian glands, and also may decrease the risk of future episodes of meibomian gland dysfunction.
Fish such as salmon, sardines, herring, and cod; nuts including flaxseed, chia seeds, and walnuts are a natural rich source of omega-3 fatty acids and should be included in daily diet.
References
- Bron AJ, Benjamin L, Snibson GR. Meibomian gland disease. Classification and grading of lid changes. Eye (Lond) 1991;5 ( Pt 4):395-411.
- Shirakawa R, Arita R, Amano S. Meibomian gland morphology in Japanese infants, children, and adults observed using a mobile pen-shaped infrared meibography device. Am J Ophthalmol 2013;155:1099-103 e1.
- Knop E, Knop N, Millar T, Obata H, Sullivan DA. The international workshop on meibomian gland dysfunction: report of the subcommittee on anatomy, physiology, and pathophysiology of the meibomian gland. Invest Ophthalmol Vis Sci 2011;52:1938-78.
