Download Challenges in Dry Eye Research - American Academy of Optometry

Challenges in Dry Eye Research
William Ngo, OD FAAO
Centre for Contact Lens Research
University of Waterloo, School of Optometry & Vision Science
200 University Avenue West, Waterloo, Ontario, Canada, N2L 3G1
Email: [email protected]
Phone: 1-519-888-4567 x 31311
Fax: 1-519-888-4303
Financial Disclosure - Members of the Centre for Contact Lens Research have received
funding/honoraria from the following companies over the past 3 years; Advanced Vision Research,
Alcon, AlgiPharma, Allergan, Contamac US, CooperVision, Essilor, Johnson & Johnson Vision Care, Ocular
Dynamics, OCULUS, TearScience.
Furthermore, over the past 3 years I have received funding from the American Optometric Foundation,
Hamad Medical Corporation, Academia Puertorriquena de la Superficie Ocular y Lentes de Contacto, and
Alcon in the form of awards, honoraria, and consulting fees.
Course Description: This one-hour lecture is aimed at clinicians who wish to learn or further understand
the nature of dry eye research. A brief introduction and review of dry eye disease is presented first. This
will be followed up with a discussion on some characteristics of dry eye disease that can make dry eye
research particularly frustrating. The main challenges are the lack of standardization of tests, restrictive
participant entry criteria, and lack of correlation between symptoms and signs.
Outline of course, 1 hour
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Title of presentation, name of presenter, affiliation
Financial and conflict of interest disclosures
Introduction and review
o Prevalence of dry eye
 summary from DEWS epidemiology
o Symptoms of dry eye
 burning, stinging, grittiness, fluctuating vision
o Effect on quality of life
 Frustration with visual discomfort
 Uncomfortable reading and computer use
 Air conditioned and low humidity areas
o Relevant anatomy
 Lacrimal gland
 Meibomian glands
 Conjunctival goblet cells
o Etiology of dry eye
 Aqueous deficiency
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 Evaporative dry eye
o Risk factors for dry eye
 Not enough omega 3 fatty acids
 Computer use
 Contact lens wear
 Refractive surgery, etc.
o Evolution of the definition of dry eye
Challenges with dry eye research
o Restrictive participant selection for clinical studies
 different etiology requires for different management strategies
 appropriate treatment for one type is different than another other
 e.g. medicamentosa dry eye vs. contact lens dry eye vs. meibomian gland
dysfunction
 different types of dry eye usually overlap with each other, e.g. sjogren’s dry eye with
meibomian gland dysfunction, and contact lens dry eye with meibomian gland
dysfunction
o Lack of standardization of tests
 Review of basic tests and their variations
 Symptom questionnaires
o Advantages/disadvantages
o Association between dry eye symptoms with other conditions, e.g.
depression/glaucoma/convergence insufficiency
 Tear stability (TBUT)
o Invasive vs non-invasive
o Volume and concentration of fluorescein inconsistent
 Tear quantity (Schirmer’s)
o Insertion for Schirmer strip not standardized (nasal, central, or
temporal)
o Direction of gaze
o Use of anesthetic
 MG function/meibum assessment
o Variety of meibum expression techniques, varying pressures, gland
counting
 Ocular surface staining
o No standard of fluorescein instillation volume
o Time between instillation to grading not usually clear
o Many different grading scales, e.g.
 Sjogren’s International Collaboration Clinical Alliance
 Oxford staining scale
 Eyelid margin health
o No universal standard grading for erythema, telangiectasia, edema,
notching
 Climate of testing affect dry eye tests
 Drier areas show worse scores
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Lack of correlation between symptoms and signs
 Dry eye tests do not follow disease in a predictable pattern, which can make it
difficult to apply study findings
 Dry eye test values usually have a large “normal” range and a very narrow “severe
dry eye” range, and can vary widely e.g.
 NIBUT <5s = dry eye, but anything >10s = normal
 Schirmer’s < 10mm = dry eye, but 11-35mm = normal
 Lack of correlation between signs, and lack of correlation between symptoms and
signs
 Approximately half of patients with dry eye report symptoms that were consistent
with disease state
 Which means there are patients with dry eye who do not experience
discomfort. How do results of studies that enrol symptomatic patients apply
to asymptomatic ones?
 Perhaps symptoms should be thought of as an aspect of dry eye, and other
clinical tests measure other separate aspects of dry eye
Summary
o Participants for clinical trials may be difficult to recruit for due to the multifactorial etiology
of dry eye
o Lack of standardization of tests make it difficult to compare results across studies and
clinical practice
o Lack of correlation between dry eye signs make data analysis frustrating. We may also be
missing asymptomatic dry eye participants.