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A New Paradigm for Dry Eye
The Academic to the Pragmatic
Donald R. Korb, O.D.
Boston, MA
American Academy of Optometry
Phoenix, AZ, October 2012
2-Hour Course
ABSTRACT
MGD is the leading cause of dry eye. A new model for the Dry Eye Cascade,
including proposed mechanisms for how hyposecretory MGD, frequently nonobvious, cascades in to anatomical and atrophic changes of the ocular surface
and adnexa which ultimately obscure the root cause of the dry eye − MGD.
Clinical treatment and prevention are also addressed.
SYNOPSIS
Status of Dry Eye: Dry eye is the leading reason for visits to optometrists and
ophthalmologists in the US. Dry eye is also the leading cause of contact lens
intolerance leading to discontinuation of contact lens wearing. Treatment of dry
eye has proven to be less than optimal.
A New Direction for Dry Eye: A change in direction for the understanding of dry
eye etiology and treatment was highlighted by the 2011 Report of the
International Workshop on Meibomian Gland Dysfunction summary statement:
“MGD may well be the leading cause
of dry eye disease throughout the world.” (IOVS, 2011)
This dramatic shift from the traditional aqueous and mucous-based models for
dry eye to inclusion and emphasis of meibomian gland dysfunction resulted in an
explosion of interest and research and qualifies as a true paradigm shift, as
defined by the nomenclator of the term paradigm shift, Thomas S. Kuhn
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LECTURE FOCI
This lecture will present:
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The evidence for supporting this new paradigm of dry eye etiology,
diagnosis and treatment, including the ever-expanding role of meibomian
gland dysfunction and obstruction, and a new clinical entity, Non Obvious
Obstructive Meibomian Gland Dysfunction (NOMGD). NOMGD has
particular relevance to contact lens practice.
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A recently introduced diagnostic instrument for meibomian gland
evaluation, which has allowed the evaluation and quantification of
individual meibomian gland functionality and correlations to ocular
symptoms and signs.
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Diagnostic methods including recently approved FDA diagnostic
modalities.
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Emphasis will be placed on how this research provides a practical clinical
approach for the diagnosis and management of dry eye patients in clinical
practice.
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The relevance of NOMGD to the tear film and to lid wiper epitheliopathy
allowing an understanding of how this new paradigm relates to dry eye
etiology, pathogenesis, prevention and treatment.
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The relevance of the Line of Marx
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Dichotomies and anomalous findings encountered in dry eye conditions
and disease – particularly aqueous vs evaporative dry eye
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Reimbursement and Coding
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The author’s new model for the Dry Eye Cascade, including a proposed
mechanism of action to explain how minimal hyposecretory MGD,
frequently non obvious, cascades in to anatomical and atrophic changes
of the lids, meibomian glands, cornea, mucous secretory system and
lacrimal gland until the magnitude of the changes obscure the root cause
− meibomian gland obstruction. This model provides an understanding for
the treatment and prevention of the most frequently encountered − the
vast majority of dry eye.
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Dry Eye
Why do we care about Dry Eye?
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High prevalence
Rapidly changing non-blinking environment with ever increasing use of
electronic mobile media and computers
Average age of onset is decreasing due to lifestyle - now includes children
A public health issue
Aging population
Dietary concerns
Contact lens wear
Surgical outcomes - Lasik - Aphakia
Dry eye has come looking for us…. With today’s lifestyle we cannot ignore
dry eye.
Definition: “Dry eye is a multi-factorial disease of the tears and ocular
surface that results in symptoms of discomfort, visual disturbance and tear
film instability with potential damage to the ocular surface. It is
accompanied by increased osmolarity of the tear film and inflammation of
the ocular surface.” (DEWS report 2007)
Etiopathogenic classification of dry eye – the 2007 DEWS report
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The contemporary model of dry eye was established by the 2007 DEWS
report.
○ Systemic, behavioral, and environmental factors
○ Aqueous deficient dry eye vs. evaporative dry eye
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The role of inflammation
o Is inflammation the cause of dry eye?
o Is inflammation a sequela of many dry eye states?
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The role of autoimmune disease
Meibomian Gland Dysfunction (MGD)
Definition: "Meibomian gland dysfunction is a chronic, diffuse abnormality
of the meibomian glands, commonly characterized by terminal duct
obstruction and/or qualitative/quantitative changes in the glandular
secretion. This may result in alteration of the tear film, symptoms of eye
irritation, clinically apparent inflammation, and ocular surface disease.”
(Report of the International Workshop on Meibomian Gland Dysfunction, IOVS,
2011)
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Diagnosis and Classification of MGD
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Normal
Hypersecretion (seborrheic)
Obstructive MGD
o Hyposecretion
o Frequently non obvious
Inflammatory MGD (pouting & plugging)
Infective MGD (glands and/or lids)
However, specific classification and diagnosis of MGD is rarely practiced due to a
combination of factors including less than precise definitions for the types of
MGD, the lack of instrumentation providing quantitative data, and the highly
subjective methods of evaluation. These problems have prevented
comprehensive diagnosis of MGD and the specific type of MGD, resulting in an
under appreciation of the role of MGD in dry eye conditions and frequently
inadequate treatment.
Meibomian Glands – New Information and a New Expanding Role
Key statement: “MGD may well be the leading cause of dry eye disease
throughout the world.”
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Requires understanding of definition of MGD and MG functionality
Meibomian Gland Function and Functionality
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Functions of meibomian glands – minimize evaporation, tear film
stability, vision, lubrication
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Concept of a functional meibomian gland
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How is MG functionality determined and quantified?
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Meibomian gland secretion dependent upon blinking
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What is MGD? A practical definition
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Development of instrumentation for diagnosis of MG functionality
and quantification
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Specific MG activity at any given time?
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Correlation between numbers of MG yielding liquid secretion
(MGYLS) to dry eye symptoms?
o The mean number of meibomian glands yielding liquid secretion
(MGYLS) in nasal, central & temporal regions of the lower eyelid
– all areas are not equal – a surprising finding
o Time required for a single optimally secreting MG to recover after
being drained of available oil
o Diurnal variations in MG yielding liquid secretion
o Variations in meibomian excreta with expression and the force of
expression
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Lid Wiper Epitheliopathy (LWE) – Frequently the Missing Link
Definition: Lid Wiper is that aspect of the marginal conjunctiva of the upper
eyelid that wipes the ocular surfaces during blinking
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A missing link in dry eye diagnosis, treatment and contact lens comfort
Windshield wiper analogy
Prevalence
Diagnosis and grading of LWE
o The use of stains in diagnosis
Correlation of LWE to dry eye signs and symptoms
Evidence based medicine for LWE – the studies
Causative factors of LWE – inflammation, lubrication, mechanical
The role of the lid wiper in ocular sensation and symptoms
The lid wiper and lid wiper epitheliopathy in contact lens practice
The role of the lid wiper in exacerbating dry eye and inflammation
Treatment of LWE
FOCUS ON LUBRICITY OF TEAR FILM AND LWE
History – Symptoms
 The Gold Standard for dry eye diagnosis
 Survey of preferred tests for diagnosis of the tear film and dry eye. (Korb,
Cornea 19;483-6, 2000)
 OSDI questionnaire
 Speed questionnaire
THE LINE OF MARX – A NEW AREA
 Role
 Diagnostic Value
 Treatment
The Role of Interferometry
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Instrumentation – Interferometers
The LipiView – A new computerized interferometer
Measurement of lipid layer thickness and characteristics
Correlation of lipid layer thickness to dry eye symptoms
Correlation to meibomian gland expressibility and function
Role in diagnosis and treatment
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Tests for Dry Eye
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History
Break-up time
Staining
Schirmer
Meibomian gland functionality
Meniscus height
Lipcof
Lipid layer thickness
Other – over 20
Meibomian Gland Obstruction
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Obstruction of the meibomian gland ducts and orifices results from
keratinized epithelial cells and secretory material aggregating in
keratotic clusters, altering MG secretion & the tear film.
Bacterial proliferation occurs in the desquamated cells of excretory
pathways of the meibomian glands.
Release bacteria & toxic products into tear film, resulting in:
o Inflamed and red eyes
o Infection
o Reoccurring inflamed – infective states post antibiotic-steroid
treatment suggests MGD
Expanded classification and understanding of MGD should include:
o Obstructive MGD without obvious inflammation but with signs of
MGD
o Non Obvious Obstructive MGD, possibly the most common
form of MGD. Requires physical expression for Dx
The paradigm shift in our understanding of Dry Eye is the result of the Tear Film
and Ocular Surface Society’s recognition of the role of MGD in 2008, and the
2011 Report of the International Workshop on Meibomian Gland Dysfunction of
this prestigious International Tear Film and Ocular Surface Society:
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Treatment of MGD
1. Replace the meibomian gland secretions
 Lipid Replacement Drops – Systane Balance
2. Increase efficacy of meibomian glands & meibomian gland secretions
 Warm compresses (WC)
 Profiles for anterior and posterior lid temperature in WC treatment
 Scrubs of lid margins
 Expression – office treatment
 Limit of expression = PAIN
○ Limits of acceptable pressure in PSI
○ Pain limits specific to individual
 Self-expression
 Commercially available devices for MG treatment
 Role of blinking
 Medications – topical and systemic
 New treatments
 2011 – FDA approval of LipiFlow
Coding – Reimbursement
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Use of Codes
Private Pay
THE DRY EYE CASCADE – A NEW PARADIGM
The author’s new paradigm – the theoretical and practical framework for
understanding and treating the dry eye cascade:
Summary – The Dry Eye Cascade is initiated by a decrease in meibomian
gland functionality, resulting in a decrease in lipid secretion and resulting
lipid layer thickness and quality. When the rate of evaporation of the
aqueous exceeds that threshold required to maintain tear film stability, a
series of sequelae result, with dry eye as an end point.
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IMPLICATIONS OF MGD
DRY EYE CASCADE
&
Stasis – Obstruction
NON – OBVIOUS MGD
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Decrease in lipid secretions
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Evaporation increases
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Decrease in aqueous layer thickness
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Unstable tear film
Sjögren’s
Syndrome
JRA
Lubricity compromised
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Microtrauma
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Lid Wiper Epitheliopathy
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Triple Response of Lewis
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Inflammation
Ocular surface compromised
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Dry eye Inflammation
Sequelae of a compromised lipid layer
Sequelae of a compromised lipid layer
Visible changes
Not Visible Changes – Specular Microscopy – 800 X
Inflammation
Cornea: Cells altered, nerve density, branching, tortuosity, neuromas,
dendritic cells
Palpebral and bulbar conjunctivitis
Lids: Fibrosis, inflammatory cells, MG damage
Anatomical changes to external surfaces,
lid margins, Line of Marx
SEVERE INTERNAL INFLAMMATION, FIBROSIS & ATROPHY
Sequelae of a compromised lipid layer
 Does lacrimal gland up-regulate, overwork leading to atrophy ?
 Diabetic & adrenal analogue
Treat MGD early to:
Prevent visible and non-visible lid and corneal changes
Prevent MGD & Dry Eye
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SUMMARY of DRY EYE CASCADE
Lipid deficiency & not aqueous deficiency is usually the catalyst for the DRY EYE
& inflammatory cascade.
Backward to conventional models and treatment
MGD and MG OBSTRUCTION may be obvious or non-obvious, most frequently
non-obvious, particularly in contact lens practice.
Stasis and obstruction of the meibomian glands leads to decreased secretion
and increased evaporation with the sequela of dry eye.
Dx of MG functionality requires expression – new metrics
Sequelae and mechanism of action of MGD – MGO over years
Stasis and Obstruction
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Decrease in lipid
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Increases evaporation of aqueous
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Compromises tear film thickness and lubricity
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Leads to microtrauma and LWE
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Inflammation of Ocular Surface and Lid Wiper
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Inflammatory cascade
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Conjunctivae & posterior blepharitis
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Compromised conjunctiva – infection from pathogens – staph
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Sequelae – complex disease and unable to Dx root cause
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Anatomical changes to external surfaces, lid margins, Line of Marx
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Non Visible Changes – Specular Microscopy – 800 X
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Does lacrimal gland up-regulate, overwork & atrophy?
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Maximizing the function of the meibomian glands
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Treat all blepharitis – treat cause
Tx of MG & MGD should be started early – dental analogy
Role of drugs
Heating – lid hyperthermia not ideal but mandatory Tx
Forceful expression
2011 – New Modality – FDA approved LipiFlow
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