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This lecture will present a new paradigm for the etiology, diagnosis and treatment of dry eye and the evidence based medicine supporting this new paradigm, including the everexpanding role of meibomian gland dysfunction and the new concept of meibomian gland functionality. Emphasis will be placed on how this research provides a practical clinical approach for the diagnosis and management of dry eye patients in everyday practice. Diagnostic methods and treatment modalities and the authors’ new recommendations will be presented.
- A framework of reference for a new paradigm
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Is there a need for a new approach – is current understanding, diagnosis and treatment effective?
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Is dry eye a single or multifactorial entity?
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Is dry eye aqueous or lipid deficient? Is there a difference and does contemporary thinking adequately explain aqueous and/or lipid deficient states?
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Why is there no correlation between signs and symptoms of dry eye?
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What are the initiating factors for dry eye?
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Are diagnostic methods adequate?
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Do diagnostic tests allow diagnosis and/or explain aqueous and/or lipid deficient states?
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What are the preferred diagnostic tests and what information do they provide?
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What is role of blinking in dry eye?
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Is posterior blepharitis synonymous with meibomian gland dysfunction?
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Is current treatment adequate and are the physiological and pathological components of dry eye addressed?
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Is dry eye a definitive disease or a rubric for many conditions?
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Is there currently a level of anomalous clinical and scientific results which force questioning whether areas of present dry eye science and treatment are inadequate and force the adoption of a new paradigm? And what would that paradigm be?
Definition of Dry Eye:
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)
Contemporary models of the ocular surface

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Etiopathogenic classification of dry eye – the 2007 DEWS report
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The contemporary model of dry eye was established by 2007 DEWS report.
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Systemic, behavioral, and environmental factors
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Aqueous - deficient vs. evaporative dry
Meibomian Gland Dysfunction (MGD)
The diagnosis and classification of MGD is arbitrary
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Hypersecretion (seborrheic)
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Inflammatory MGD (pouting & plugging)
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Infective MGD (glands and/or lids)
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Multifactorial disease presents a diagnostic dilemma
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Multiple tests need to be considered
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What can we test in the clinic?
Symptoms
– History, Symptom Questionnaires
Tear film stability – TBUT, aqueous secretion, lipid layer thickness, meniscometry
Ocular surface integrity
– staining (NaFl, RB, LG): cornea, conjunctiva, lid wiper,
Marx line
Meibomian gland function – diagnostic expression, meibometry
Tear film osmolarity – commercially available osmometer
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Practical sequence of testing
Clinical history
Symptom Questionnaire
Interferometry if available
Slit lamp evaluation
FBUT (DET)
Ocular surface staining – combining stains
Schirmer testing
Lid and meibomian morphology
Meibomian expression
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A Missing Link in Dry Eye Diagnosis and Treatment
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Lid Wiper defined – that aspect of the marginal conjunctiva of the upper eyelid that wipes the ocular surfaces during blinking
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Windshield wiper analogy
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Lid wiper epitheliopathy (LWE) defined
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Diagnosis and grading of LWE
The use of stains in diagnosis

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Correlation of LWE to dry eye signs and symptoms
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Causative Factors of LWE – inflammation, lubrication, mechanical
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The role of the lid wiper in ocular sensation and symptoms
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Treatment of LWE
Expanding role of meibomian glands: Meibomian gland dysfunction may be the leading cause of dry eye syndrome throughout the world.
Requires precise understanding and defining MGD and MG functionality
Distinguish between posterior blepharitis and MGD
Meibomian Gland Function
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Functions of MG
– evaporation, tear film stability, vision, lubrication
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What is a normal functional meibomian gland ?
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Meibomian gland secretion dependent upon blinking
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What us MGD ? A practical definition
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How is MG functionality determined and quantified?
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Specific MG activity at any given time?
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Development of instrumentation for quantification of MG function.
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Correlation between numbers of MG yielding liquid secretion (MGYLS) to dry eye symptoms?
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The mean number of MGYLS in nasal, central & temporal regions of the lower eyelid
– a surprising finding
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Time required for a single optimally secreting mg to recover after being drained of available oil
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Diurnal variations in MG yielding liquid secretion
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Variations in meibomian excreta with expression
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Why meibomian gland obstruction? Obstruction of the meibomian gland ducts and orifices by keratinized epithelial plugs and other matter.
Expanded Classification of MGD should include: Obstructive MGD without obvious inflammation
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Warm compresses (WC)
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Profiles for lid temperature in WC treatment
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Scrubs
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Expression – office treatment
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Self-expression
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Commercially available devices for MG treatment
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Role of blinking
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Medications
– topical and systemic

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Instrumentation
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Measurement of thickness and characteristics
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Correlation of lipid layer thickness to dry eye symptoms
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Correlation to meibomian gland expressibility and function
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Role in diagnosis and treatment
Presents a new framework and perspective to understand the multifactorial nature of dry eye states and disease. The new model-paradigm explains many of the dichotomies and anomalous findings encountered in multifactorial dry eye states.
The model – paradigm includes the following sequelae of a decrease in lipid layer quality and thickness beyond below that threshold required to maintain tear film stability.
Implications of MGD
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
Ocular surface compromised
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Dry eye Inflammation
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
Palpebral and Bulbar conjuctivitis
Posterior blepharitis

Sequelae of a compromised lipid layer
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Does lacrimal gland up-regulate & overwork?
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Diabetic & adrenal analogues
Treat MGD early to prevent
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Inflammation of ocular surface
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Lacrimal gland inflammation
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LWE
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Dry eye
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