Post on 30-Dec-2016
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Tear Osmolarity and its’ role in Optometric Practice
& Contact Lens Success
Nick Dash: OptometristDeclaration of AssociationDirector: See2wiN Ltd (Accuvision/Visual Edge/SportsVision Institute)Honorary Lecturer Cardiff University: Dept. OptometryBSc Cell Biology & Immunology: University SouthamptonDirector: Sports Vision Institute, LoughboroughFounder of www. SkiCPD.org Currently no commercial interests in Third Party Companies
Understanding the Optics of the Eye
Optical Media Refractive IndexAir 1.00Tear film 1.34Cornea 1.38Aqueous humor 1.33Crystalline lens 1.41Vitreous humor 1.34
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.
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)
• 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. 920231 Rev B
Percentage of patients suffering from symptoms who report experiencing the symptoms at least 3-4 times per week or more.
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.”
4International Dry Eye Workshop (DEWS). The definition & classification of dry eye disease. Ocul Surf 2007.
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Majority of DED Patients Have Evaporative Dry Eye Disease (EDED)
• 86% of patients with a classified DED subtype demonstrated signs of Meibomian Gland Dysfunction
• Pure Aqueous Deficient Dry Eye (ADDE) subtype represented the smallest percentage of patients (~10%)
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ADDEEDEDOther
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. 920231 Rev B
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
6Nichols KK. The Lack of Association Between Signs and Symptoms in Patients with Dry Eye Disease. Cornea 2004; 23(8) 762-770.
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Why Measure Tear Osmolarity?
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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. Sullivan BD et al. An objective approach to dry eye disease severity. IOVS 2010;41(12): 6125-6130. 920231 Rev B
Osmotic Pressure – Cellular Effect
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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
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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 920231 Rev B
Hyperosmolarity Causes loss of Micropilae on the Corneal Epithelium
10Andrews PM. Journal Cell Bio. 1976;68:420–429920231 Rev B
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Hyperosmolarity Causes loss of Microplicae – Schematic Representation
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Hyperosmolarity Causes loss of Microplicae
12Gilbard JP. CLAO J. 1985;11(3):243
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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.
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
MAXIMUM of the two eyes: >300 mOsm/L demonstrates loss of homeostasis and likely to become pathogenic >308
DIFFERENCE between two eyes: 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 Variability mOsm/L > 20 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.
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Protocol for ‘Dry Eye’ or ‘Ocular Surface Disease’
Questionnaire (OSDI) Lids Staining Tear Break-up Osmolarity
Dry Eye Tests
Tear Osmolarity Is the Best Predictor of Disease SeverityTBUT
OSDI Corneal Staining
Osmolarity
Meibomian Scoring
Conjunctival Staining
Schirmers
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
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What treatment strategies we implement do they work?
If so do they correlate with improvements in Osmolarity?
Tear Osmolarity Measures Effective TreatmentHyaluronic Acid (HA) Carboxymethyl cellulose (CMC)
Optom Vis Sci. 2013 Apr;90(4):372-7 Montani Giancarlo Optometrist FIACLE, Dept di Optometria, Università del Salento
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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. 920231 Rev B
Reduction in Osmolarity Predicts Symptom Response
Sullivan BD, et al. Cornea 2012.
• 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.
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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 withOSP -
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.
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?
Addressing Dry Eye as a Niche or core service
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
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.
Engage and Inform patients relate it to their terms or needs:
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.