Download tear film instability

Tear Osmolarity and its’ role in
Optometric Practice
& Contact Lens Success
Nick Dash: Optometrist
Declaration of Association
Director: See2wiN Ltd (Accuvision/Visual Edge/SportsVision Institute)
Honorary Lecturer Cardiff University: Dept. Optometry
BSc Cell Biology & Immunology: University Southampton
Director: Sports Vision Institute, Loughborough
Founder of www. SkiCPD.org
Currently no commercial interests in Third Party Companies
1
Understanding the Optics of the Eye
Max difference in refractive index at air –
tear film/cornea interface –
Tear film is the optical surface that has
biggest impact on light when travelling
through air into the eye.
Optical Media
Refractive Index
Air
1.00
Tear film
1.34
Cornea
1.38
Aqueous humor
1.33
Crystalline lens
1.41
Vitreous humor
1.34
Optics Of The Tear Film
• Tear film stability is critical for the
maintenance of visual quality
• Uniform reductions of tear film thickness
have little effect
• Irregular thickness degrades image
quality
• Patients with Dry Eye have larger optical
aberrations compared with normal eyes
(by a factor of ~2.5)
Percentage of patients suffering from symptoms
who report experiencing the symptoms at least
3-4 times per week or more.
• Artificial tears reduce these
abnormalities and improve image
quality in patients with Dry Eye
Montes-Mico R. Role of the tear film in the optical quality of the human eye. J Cataract Refract Surg. 2007;33:1631-1635.
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DEWS Dry Eye Definition
•“Dry eye is a multifactorial 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.”
International Dry Eye Workshop (DEWS). The definition & classification of dry eye disease. Ocul Surf 2007.
920231 Rev B
4
Majority of DED Patients Have Evaporative Dry Eye Disease (EDED)
• 86% of patients with a
classified DED subtype
demonstrated signs of
Meibomian Gland Dysfunction
ADDE
EDED
Other
• Pure Aqueous Deficient Dry
Eye (ADDE) subtype
represented the smallest
percentage of patients (~10%)
Lemp MA, et al. Cornea. 2012;31:472-478.
Regardless of the underlying cause, hyperosmolarity is
present*
*International Dry Eye Workshop (DEWS). The definition & classification of dry eye disease. Ocul Surf 2007.
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5
Challenges in Dry Eye Disease
• Patients often present with conflicting signs
• Low Schirmer’s (< 5 mm) with a high TBUT (> 7 seconds)
• Evidence of staining, but normal Schirmer’s and TBUT
• Symptoms alone are not diagnostic and insufficient to determine
severity
• Questionnaires are nonspecific
• Patients are unsatisfied with current standard of care; they move from practice to
practice seeking better options
• Existing signs and tests correlate poorly with disease severity
• Schirmer’s, TBUT, staining may not correlate with each other or symptoms
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Nichols KK. The Lack of Association Between Signs and Symptoms in Patients with Dry Eye Disease. Cornea 2004; 23(8) 762-770.
6
Why Measure Tear Osmolarity?
Measuring osmolarity allows us to evaluate an
objective physiologic marker rather than
relying only on subjective signs of the disease
such as staining or tear break up time.
Baudouin C et al. Diagnosing the severity of dry eye: a clear and practical algorithm. Br J Ophthalmol 2014;98:1168-1176.
920231 Rev B
Sullivan BD et al. An objective approach to dry eye disease severity. IOVS 2010;41(12): 6125-6130.
7
Osmotic Pressure – Cellular Effect
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8
Inter-eye Differences in Dry Eye Disease (DED)
R = L
• The Dry Eye process is characterized by a loss of tear film homeostasis
resulting in hyperosmolarity and an unstable tear film
• Dry Eye is a bilateral and often asymmetrical disease
• Inter-eye difference >8 mOsm/L is an indication of tear film instability,
frequently an early manifestation in the development of disease
• DED has either eye >295 mOsm/L
• Normal Tear Film (Dry Eye)
• Tears in proper homeostasis should be equivalent to blood osmolarity
which is between 280-295 mOsm/L
• Inter-eye osmolarity difference should be <8 mOsm/L
International Dry Eye Workshop (DEWS). The definition & classification of dry eye disease. Ocul Surf 2007.
Lemp MA, Bron AJ, Baudouin C, Benítez Del Castillo JM, Geffen D, Tauber J, Foulks GN, Pepose JS, Sullivan BD. Tear osmolarity in
the diagnosis and management of dry eye disease. Am. J. Ophthalmol. 2011 May; 151(5):792-798.
Keech A, Senchyna M, Jones L. Impact of time between collection and collection method on human tear fluid osmolarity. Curr. Eye
Res. 2013 Apr; 38(4):428-36
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9
Hyperosmolarity Causes loss of Micropilae on the
Corneal Epithelium
Andrews PM. Journal Cell Bio. 1976;68:420–429
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10
Hyperosmolarity Causes loss of
Microplicae – Schematic Representation
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11
Hyperosmolarity Causes loss of Microplicae
Gilbard JP. CLAO J. 1985;11(3):243
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12
Hyper-osmolarity: a Core Mechanism of Dry Eye
• The core mechanisms of dry eye are driven by
tear hyperosmolarity and tear film instability
• Hyperosmolarity causes damage to the surface
epithelium by activating a cascade of
inflammatory events at the ocular surface and
a release of inflammatory mediators into the
tears
• Epithelial damage involves cell death by
apoptosis, a loss of goblet cells, and disturbance
of mucin expression, leading to tear film
instability
• Instability exacerbates ocular surface
hyperosmolarity and completes the vicious
circle
International Dry Eye Workshop (DEWS). The definition & classification of dry eye disease. Ocul Surf 2007.
920231 Rev B
Dry Eye Cycle
Hyperosmolarity perpetuates the Cycle of TF Instability
How is osmolarity
measured?
TearLab Osmolarity System
Tear Collection
Measurement of Both Eyes is Essential
DIFFERENCE between two
eyes:
MAXIMUM of the two eyes:
>300 mOsm/L demonstrates
loss of homeostasis and likely
to become pathogenic >308
Shows the stability of the
tear film. Normal tears are
stable and <300 mOsm/L
bilaterally. A difference of >8
mOsm/L is a hallmark of tear
instability
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Effect of Compensatory Mechanisms in
Early Stage DED
Blinking, aqueous tearing (mixing), increased lipid
secretion excretion - all lower osmolarity transiently
and asymmetrically
< 5 mOsm/L
A Bron, et al. The Ocular Surface 2009 Apr;7(2) 78-92.
A Keech, et al. Curr Eye Res 2013 Apr;38(4) 428-36.
Variability mOsm/L
> 20 mOsm/L
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Dry Eye Tests
Protocol for ‘Dry Eye’ or ‘Ocular Surface Disease’
Questionnaire (OSDI)
Lids
Staining
Tear Break-up
Osmolarity
Tear Osmolarity Is the Best Predictor of Disease Severity
Schirmers
OSDI
TBUT
Corneal Staining
Meibomian Scoring
Conjunctival Staining
Osmolarity
Sullivan BD, et al. Invest Ophthamol Vis Sci. 2010
51:6125-6130.
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One Px had 3 kCyl D
difference between
visits
Tear Film Placido Disc Image Before
and After Dry Eye Treatment
Before
After
Tear Film Osmolarity Correlates
with Response to Therapy
What treatment strategies we implement do they work?
If so do they correlate with improvements in Osmolarity?
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Tear Osmolarity Measures Effective Treatment
Hyaluronic Acid (HA)
Optom Vis Sci. 2013 Apr;90(4):372-7
Montani Giancarlo Optometrist FIACLE, Dept di Optometria, Università del Salento
Carboxymethyl cellulose (CMC)
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Osmolarity Showed a Decrease in BOTH Absolute
Value and Variabilty After Treatment with HA
Nelson JD, Farris RL. Arch Ophthalmol. 1988; 106: 484-487.
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Reduction in Osmolarity Predicts Symptom Response
• Bilateral tear osmolarity, Schirmer, tear film breakup time (TBUT), staining, meibomian grading, and
Ocular Surface Disease Index were measured for a period of 3 consecutive months
• Participants (n = 52) were recruited from a clinic-based population at 2 study sites.
• After a 3-month observation period, severe dry eye patients were prescribed topical cyclosporine A
and evaluated for an additional 3 months.
Sullivan BD, et al. Cornea 2012.
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Conclusion
• Hyperosmolarity affects tear film instability and leads to ocular
surface damage
• Osmolarity has a place within a well defined DE protocol
• Spectacle Rx can be improved by treating tear film instability
• Multifocal and astigmatic Rx
• Osmolarity can be used as a predictor to CL fitting success
• Contact Lens fitting can be improved by:
• Better lens selection (based on osmolarity reading)
• Providing Therapy prior and during CL wear times
Application to Contact Lens fitting
• Establish root cause:
• Aqueous deficient or Evaporative DE
• Or other eg Allergy
• Severity
• Inter-eye instability
How does osmolarity testing compare to
other test routinely done for CL fitting.
Questions we should ask ourselves.
What tests do we perform in contact lens fitting or aftercare?
How specific and sensitive are these?
Contact Lens Fitting with
OSP Ocular Surface Protocol
Need for Objective Measures
Bottom Line
Will Px pay for it?
Market 10% women in UK suffer from dry eye
Pay £s rather than in Symptoms before initiates
‘Inflammatory Cascades’.
Front office selling.
Prescribe and protect patient base
Direct Charge & Debit Grading Base (Fee Based
Approach: Consult + £??.00d/d).
Revenue stream similar to Contact Lenses.
Revenue as a add-on to standard contact lens charge.
Opportunity of outsourcing from Ophthalmologist into
Optometric Clinic. Dry Eye / Ocular Surface and lid
conditions.
Addressing Dry Eye as a Niche or core service
Wealth?
In the UK 16 million dry eye vrs 18 million myopes
(<4 Million Contact Lens Wearers)
dry eye industry in UK £ 224 Million (Growing+++)
contact lens industry £250 Million
Whats it worth to you?
Dry Eye, Measure & Management?
PEARLS OF WISDOM!
Need a metric…. as High Blood Pressure.
Objective Metric (Osmolarity) offers,
diagnosis,
treatments tracking,
endorses treatment regimen and lens selection,
offers medico-legal justification of treatments or lens selection,
greater patient engagement and appreciation of dry eye as
chronic ongoing condition,
improves patient compliance,
differentiate you from other clinicians
Engage and Inform patients relate it to
their terms or needs:
PEARLS OF WISDOM!
Understand dry eye & CLs
Dry eye is endemic and there is
no cure to Dry Eye.
So it exists as stand alone and a
co-morbidity to Contact Lenses.
‘No CURE’ it requires
management on an ongoing basis.
Continuity of care that includes
clinically robust objective
measures to support healthy eyes.
Reduce wrinkles and clear the whites,
akin to skin night and day creams (a
beauty product)
Selling dry eye as youthful white
comfortable eyes.
White quiet and comfortable.
Thank you
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