Meibomian gland dysfunction (also known as MGD) is a chronic

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

of the meibomian glands, 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 to reach 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 Blepharitis is one of the most common ocular conditions characterized by inflammation, scaling, reddening, and crusting of the eyelid. This condition may also cause swelling, burning, itching, or a grainy sensation when introducing foreign object ...

chalazion A chalazion (; plural chalazia or chalazions) or meibomian cyst is a cyst in the eyelid usually due to a blocked meibomian gland, typically in the middle of the eyelid, red, and not painful. They tend to come on gradually over a few weeks. A ...

, 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 Lipase ( ) is a family 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; however, these are usually ...

s, resulting in the formation of free

fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, f ...

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 (DES), also known as keratoconjunctivitis sicca (KCS), is the condition of having dry eyes. Other associated symptoms include irritation, redness, discharge, and easily fatigued eyes. Blurred vision may also occur. Symptoms range ...

. Factors that contribute to the dysfunction can include things such as a person's age and/or hormones, or severe infestation of Demodex brevis mites. Treatment can include

warm compresses A warm compress is a method of applying heat to the body. Heating sources can include warm water, microwaveable pads, wheat packs and electrical or chemical pads. Some unorthodox methods can include warmed potatoes, uncooked rice, and hard-boiled ...

to thin the secretions and eyelid scrubs with

baby shampoo Baby shampoo /ˈbeɪbi/ /ʃæmˈpuː/ is a hair care product that is used for the removal of oils, dirt, skin particles, dandruff, environmental pollutants and other contaminant particles that gradually build up in hair; specially formulated fo ...

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 a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...

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 bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...

s (to reduce bacteria on the lid margin) are also prescribed to reduce inflammation. Intense pulsed light (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 primarily used to treat severe acne. It is also used to prevent certain skin cancers (squamous-cell carcinoma), and in th ...

. A blocked meibomian gland can cause a meibomian cyst known as a

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 abuse, also known as drug abuse, is the use of a drug in amounts or by methods which are harmful to the individual or others. It is a form of substance-related disorder. Differing definitions of drug abuse are used in public health, ...

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 skin condition that occurs when dead skin cells and oil from the skin clog hair follicles. Typical features of the condition include blackheads or whiteheads, pimples, oily skin, and ...

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.

References

{{Eye pathology Eye diseases

Classification

See also

References