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  • 1

    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.

    920231 Rev B

  • 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%)

    5

    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 Schirmers (< 5 mm) with a high TBUT (> 7 seconds) Evidence of staining, but normal Schirmers 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

    Schirmers, 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.

    920231 Rev B

  • Why Measure Tear Osmolarity?

    7

    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

    8920231 Rev B

  • 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

  • Hyperosmolarity Causes loss of Micropilae on the Corneal Epithelium

    10Andrews PM. Journal Cell Bio. 1976;68:420429920231 Rev B

  • 11

    Hyperosmolarity Causes loss of Microplicae Schematic Representation

    920231 Rev B

  • Hyperosmolarity Causes loss of Microplicae

    12Gilbard JP. CLAO J. 1985;11(3):243

    920231 Rev B

  • 920231 Rev B

    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 8 mOsm/L is a hallmark of tear instability

    920231 Rev B

  • 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.

    920231 Rev B

  • 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.

    920231 Rev B

  • 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

    920231 Rev B

    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, Universit del Salento

    920231 Rev B

  • 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.

    920231 Rev B

  • 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.

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