Meibomian Gland Dysfunction: What Does It Mean

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Meibomian Gland Dysfunction: What Does It Mean James P. McCulley, MD, FACS, FRCOph(UK) David Bruton, Jr. Professor of Ophthalmology Chairman, Department of Ophthalmology The University of Texas Southwestern Medical School Dallas, Texas

No relevant financial relationships to disclose.

Primary e.g. Hypersecretory Secondary/Contributory e.g. with ADDE Epiphenomenon/Marker for disease e.g. “IOSD” with induction of hyper keratinization Aging –normal vs contribute to “dry eye” All/Each of the above

Tear Film Instability

ƒ Lipid Deficiency

– Cause: meibomian gland dysfunction (MGD) causing insufficient or unhealthy lipid production – Sign: irregular meibomian gland expression, fast tear film break-up time (TFBUT)

ƒ Aqueous Deficiency – Cause: insufficient tear production by accessory and primary lacrimal glands – Sign: low Schirmer (tear volume/flow) score

ƒ Mucin Deficiency – Cause: insufficient or unhealthy mucin production – Sign: TFBUT

Lipid Layer The Antievaporative Layer ¾ Outermost layer of the tear film ¾ Approximately 0.1 ȝm thick ¾ Primary function = prevent evaporation & overflow of tears ¾ Produced by meibomian glands along the lower and upper lids. OCULAR SURFACE

Definition of MGD Meibomian gland dysfunction (MGD) is a chronic, diffuse abnormality of meibomian glands, characterized by an alteration in the qualitative and/or quantitative secretion of the meibomian glands that may result in alteration of the tear film, symptoms of eye irritation, clinically apparent inflammation, and ocular surface disease.

Clinical Characteristics of MGD Lid margin neovascularization

Squamous metaplasia of meibomian gland orifices

SYMPTOMS of “dry eyes” 

Burning



Itching



Excessive tearing



Granular sensation and scratchiness or foreign-body sensation due to crusted debris or dryness



Decreased vision or changes in visual clarity due to poor tear film



Eyelids stuck together upon waking



Crusty debris around the eye lashes, especially upon waking Eyelids red, especially upon waking



Meibum “alterations” (color / composition)

Photos courtesy of Richard Yee, MD, Don Korb, MD and Justin Kwan, MD., 2010.

Gland drop out

Short TFBUT

Preferred Practice Pattern® Guidelines. Blepharitis. San Francisco, CA: American Academy of Ophthalmology; 2008. Available at: http://www.aao.org/ppp.

Meibomian Gland Dysfunction (MGD) ? n Evaporation Anatomic Definition: Meibomian gland dropout on meibography. Slit lamp Definition: Difficult to express meibum or turbid meibum on expression.

Wojtowicz, JC, Butovich, IA. McCulley, JP. Historical Brief on Composition of Human Meibum Lipids. Ocular Surface 2009 July;(7)3:145-153.

Primary Hyposecretory MGD

Hypersecretory MGD AKA Meibomian Seborrhea

Obstructive/Hyposecretory MGD

Turbid MGD

Meibomian Gland Disease

Non-obvious MGD

Photos courtesy of Justin Webb, OD, Alcon Research Ltd., 2010.

MKC “Posterior Blepharitis” ƒ Inflammation of the posterior lid margin

Zero Drop Out

Photo Courtesy of JP McCulley, MD

50.0 % Drop out

Photo Courtesy of JP McCulley, MD

Clinical Significance of MGD Theory: associated with increased tear evaporation resulting in (hyperevaporative) KCS and in (frequent) association with aqueous secretory deficiency (hyposecretory) KCS combined mechanism KCS.

McCulley JP, Uchiyama E, Aronowicz J.D, Butovich I.A, Impact of Evaporation on Aqueous Tear Loss. Trans Am Ophthalmol Soc 2006;104:121-8.

KCS: Keritoconjuntivitis Sicca

Evaporative Contribution to Tear Loss Evaporative Contribution to Tear Loss at 20-25% RH

Normals

Evaporative Contribution to Tear Loss at 40-45% RH

%

P value

%

P value

Mean

41.66 ± 23.20

(.187) *

23.47 ± 13.08

(.376) *

Mean

57.67 ± 32.25

(.114) †

30.99 ± 20.99

(.227) †

Mean

50.28 ± 35.41

(.417) †

25.44 ± 18.17

(.725) †

Dry Eye Classic KCS KCS / MGD

* Normals versus All Dry Eye † Compared to Normals McCulley JP, Uchiyama E., Aronowicz JD, Butovich IA, Impact of Evaporation on Aqueous Tear Loss. Trans Am Ophthalmol Soc 2006;104:121-8.

RH: Relative Humidity

Survey of Etiological Classification of Dry Eye % of Overall Patient Population

50%

39%

40%

30%

30%

31%

20%

10%

0% Aqueous Deficiency

MGD

Mixed

N = 40

Data on File, Alcon. Market research interviews with 40 eye care professionals asking for subjective description of the percentage of patients seen that fall into each category. Mixed refers to an unclear etiology that may contain aspects of both aqueous deficiency and lipid deficiency/MGD.

Primary e.g. Hypersecretory Secondary/Contributory e.g. with ADDE Epiphenomenon/Marker for disease e.g. “IOSD” with induction of hyper keratinization Aging –normal vs contribute to “dry eye” All/Each of the above

Aging/Menopause

Chalasis/lid margin irregularities

Blepharitis/MGD

Toxic drugs/ preservatives

Other autoimmune diseases

Rosacea Flora changes

LPS release Toxins-Lipases

Eyelid inflammation

Allergy Lipidic changes

Tear film instability Imbalance

Sjogren’s syndrome

Systemic drugs/ Antidepressants

Goblet cell loss

Cell hyperosmolarity

Cytokine release MMP activation

Cell damage

Neurogenic inflammation Lacrimal hypersecretion INFLAMMATION

Conjunctiva Cornea APOPTOSIS

Contact lens wear

Nerve stimulation

Ocular surgery LASIK/ refractive surgery

Neurotrophic

Viral/bacterial conjunctivitis

Environment

Baudouin C. Un nouveau schéma pour mieux comprendre les maladies de la surface oculaire. J Fr. Ophtalmol., 2007; 30, 3, 239-246

An Integrated Ocular Surface Complex in Health & Disease Many interactions & cascades Complex mechanisms in disease states No simple approach to pathophysiology or Rx The more we learn the more we realize how little we truly “know”