
Meibomian gland dysfunction (MGD, also meibomitis or meibomianitis) is a chronic
disease
A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...
of the
meibomian gland
Meibomian glands (also called tarsal glands, palpebral glands, and tarsoconjunctival glands) are sebaceous glands along the rims of the eyelid inside the tarsal plate. They produce meibum, an oily substance that prevents evaporation of the eye, ...
s, which is commonly characterized by obstruction of the end of the duct that delivers the secretion produced by the glands (called meibum) to the eye surface, which prevents the glandular secretion from reaching the ocular surface. The dysfunction could be that the amount of secretion produced may be abnormal (either too little or too much meibum produced). Dysfunction could also be related to the quality of the meibum produced. MGD may result in
evaporative dry eye,
blepharitis,
chalazion, unsealed lid during sleep, and meibomian gland atrophy.
MGD causes the glands to be obstructed by thick, cloudy-to-yellow, more opaque and viscous-like, oily and waxy secretions, a change from the glands' normal clear secretions.
[Peter Bex, Reza Dana, Linda Mcloon, Jerry Niederkorn (2011)]
''Ocular Periphery and Disorders''
/ref> Besides leading to dry eyes, the obstructions can be degraded by bacterial lipase
In biochemistry, lipase ( ) refers to a class of enzymes that catalyzes the hydrolysis of fats. Some lipases display broad substrate scope including esters of cholesterol, phospholipids, and of lipid-soluble vitamins and sphingomyelinases; howe ...
s, resulting in the formation of free fatty acid
In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...
s, which irritate the eyes and sometimes cause punctate keratopathy. MGD has been described as "the most underrecognized, underappreciated and undertreated disease in ophthalmic care ..so common as to be taken as ‘normal’ in many clinical practices".
The dysfunction is more often seen in women, and is regarded as the main cause of dry eye syndrome
Dry eye syndrome, also known as keratoconjunctivitis sicca, is the condition of having dry eyes. Symptoms include dryness in the eye, irritation, redness, discharge, blurred vision, and easily fatigued eyes. Symptoms range from mild and occas ...
. Factors that contribute to the dysfunction can include things such as a person's age and/or hormones, or severe infestation of Demodex brevis
''Demodex brevis'' is one of the two species of face mite that inhabit humans (the other being ''Demodex folliculorum''). They are about half as long, at 0.15 to 0.2 mm (6 to 8 thousandths of an inch), as ''D. folliculorum'', but otherwise ...
mites.
Treatment can include warm compresses to thin the secretions and eyelid scrubs with baby shampoo or eyelid cleanser, or emptying ("expression") of the gland by a professional. Lifitegrast and Restasis are topical medication commonly used to control the inflammation and improve the oil quality. In some cases topical steroid
A steroid is an organic compound with four fused compound, fused rings (designated A, B, C, and D) arranged in a specific molecular configuration.
Steroids have two principal biological functions: as important components of cell membranes t ...
s and topical (drops or ointment)/oral antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...
s (to reduce bacteria on the lid margin) are also prescribed to reduce inflammation. Intense pulsed light
Intense pulsed light (IPL) is a technology used by cosmetic and medical practitioners to perform various skin treatments for aesthetic and therapeutic purposes, including hair removal, photorejuvenation (e.g. the treatment of skin pigmentation, ...
(IPL) treatments have also been shown to reduce inflammation and improve gland function. Meibomian gland probing is also used on patients who experience deep clogging of the glands.
The dysfunction may be caused by some prescription medications, notably isotretinoin
Isotretinoin, also known as 13-''cis''-retinoic acid and sold under the brand name Accutane among others, is a medication used to treat skin diseases like harlequin-type ichthyosis, and lamellar ichthyosis, and severe cystic acne or moderat ...
. A blocked meibomian gland can cause a meibomian cyst known as a chalazion to form in the eyelid.
Untreated blepharitis or MGD makes the eyes look red and puffy as if the person have been drinking or have a substance abuse
Substance misuse, also known as drug misuse or, in older vernacular, substance abuse, is the use of a drug in amounts or by methods that are harmful to the individual or others. It is a form of substance-related disorder, differing definition ...
problem.
Classification
MGD can be classified based on gland secretion. MGD can be low delivery and high delivery. Low delivery is the most common form and is classified in hyposecretory and obstructive. Hyposecretory implies low meibum secretion without terminal duct obstruction. This is associated with gland atrophy. Contact lens wear can lead to a decreased number of functional meibomian glands. Obstructive MGD, where the terminal duct is obstructed, is the most common type of MGD. Obstructive MGD has been associated with age and acne
Acne ( ), also known as ''acne vulgaris'', is a long-term Cutaneous condition, skin condition that occurs when Keratinocyte, dead skin cells and Sebum, oil from the skin clog hair follicles. Typical features of the condition include comedo, ...
treatment products with retinoids. Obstructive MGD can be classified into noncicatricial and cicatricial. In noncicatricial, the terminal duct of meibomian glands are in their normal anatomic position. In cicatricial, they are dragged posteriorly into the mucosa.
High delivery implies an increased release of meibum into the tear surface. This has been associated with seborrheic dermatitis
Seborrhoeic dermatitis (also spelled seborrheic dermatitis in American English) is a long-term skin disorder. Symptoms include flaky, scaly, greasy, and occasionally itchy and inflamed skin. Areas of the skin rich in sebum, oil-producing gland ...
.
See also
* Meibography
A meibography is an image of the morphology of the meibomian glands. Different technologies exist to perform a meibography in a non-invasive manner. Meibography is used in meibomian gland dysfunction diagnosis.
See also
* Meibomian gland
* Dry e ...
References
{{Eye pathology
Eye diseases