Dry eye Flashcards
What keeps healthy eye comfortable and wet
tear film
- > lipid, aqueous and mucus layer
- > dry eye disease sees breakdown of squaeous and lipid layers
what is the prevalence of DED
- exact prevalence not know because of difficulty defining DED & no single diagnostic test
- 7.8-33.7% of population
- close to 3/4 of a million Canadians have dry eye disease
- prevalence is expected to increase as population of developed countries continues to age
what are the risk factors for DED
- ocular surgery
- Age > 40 years
- female gender
- medications: can decrease # of aq tears produced
- systemic diseases: diabetes, hypertension, rheumatoid arthritis, Sjogren’s syndrome, thyroid disorders etc)
- smoking
- computer vision syndrome
- environmental factors (humidity, air current/drafts, air conitioning)
- contact lens wear
what is the impact of dry eye disease on quality of life
- significantly decreased vision related quality of life, w/ inc anxiety and depression
- significantly dec funcional visual acuity
- discontinuation of contract lens wear in 1/3 of patients
- high prevalent digital eye strain syndrome
what is current definition of dry eye disease
- multifactorial disease of the ocular surface
- characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms -> tear film instability and hyperosmolarity, ocular surface inflammation and damage
- >neurosensory abnormalities play etiological roles.”
what is the main unit that is disrupted in dry eye disease
- lacrimal functional unit
what are the parts of the lacrimal functional unit
- lacrimal glands -> aqueous layer of tear film
meibomian glands -> lipid layer of tear film
ocular surface (cornea and conjunctiva) -> mucus layer of tear film
sensory and motor nerves
eye lids
*breakdown of any part of the lacrimal unit can cause dry eye disease
what is the role of tear film
- nutrition O2
- Blink
- imp for contact lens wear
- lubrication
- vision
- lid margin (inflammation here will cause there to be inadequate secretion of lipid layer
what are teh four components of the vicious circle of dry eye disease
- Tear film hyper osmolarity: environmental factors associated with dry eye
*ow humidity, wind, heat, inadequate blinking, smoking cigs
- tear film instability: factors ass with evaporative dry eye
*meibomian gland dysfunction, blepharitis, unstable tear film lipid layer, vit A deficiency, ocular allergy, contact lens wear
- Surface damage (cellular level)
- Inflammatory mediators: factors assocaited with aq deficient dry eye
*aging, low androgens, autoimmune reposnse, lactimal obsturction
*management of dry eye targets there 4 components
What are the main types of dry eye diseae classification
- aqueous deficient vs eaproative
- Evaporative
- most prevalent
- lack of quality tears (usually lipid component)
- leads to quick evaproation of tears on ocular surface
- usually due to meibomian gland dysfunction
- Aqueous deficient dy eye
- uncommon to have without overlapping signs of evaporative disease
- aqueous defiicent defined by lack of aqueous tear production by lacrimal gland
- common causes: Sjogrens syndrome, aging, systemic drugs
what are the symptoms of dry eye disease
– Foreign body sensation
– Sandy / scratchy feeling
– Burning
– Itching
– Tired eyes
– Feeling of dryness
– Increased tearing
– Vision related problems (intermittent blur, particularly later in the day)
*Symptoms tend to worsen over the course of the day, except with evaporative dry eye which is worse in the morning
how is the sevarity fo dry eye graded
Mild: good secretions
Moderate: plugging of gland, vascularization of eyelid margins
Severe: blocked meibomian ducts (thick secretions)
the msot common form of dry eye disease is
evaporative
what are goals of therapy for dry eye disease
- improve patients ocular comfort and quality of life
- return ocular surface and tear film to normal homeostatic state
what are the types of maintenance treatment for dry eye disease
- tear suplement composition: polymer/lubricant, viscoity, lipid supplements, electrolytes/buffers, osmolarity, preservaties
- evironmental: ambient humidity, air movement, computer use
peronal (ocular): hot compress/lid hydiene, moisture chambers
- personal (non-ocular): systemic medications, alcohol smoking, hormonal status, sleep apnea
what are the types of maintenance treatment for chronic (inflammatory) dry eye
Short term: topical steroid (trial)
Long term: essental Fatty acids, topical cyclosporine
Adjunctive: oral tetracyclines/macrolides, topical azithromycin
Supportive: Episodic treatments + tear preservation (lacrimal occulaion), tear film stimulation (secretagogues), meibomian gland expression (in office, lipiflow)
primary self care for evaproative or mixed DED
- tear suplements or lubricants
ocular considerations; apply hot compress, lid hygience, modifications to contact lens wear
Non-ocular considerations: environemntal modification, dietary suplments, alcohol use, smoking , hormonal status, sleep apnea
what makes a good artificial tear
Drops should:
- Reduce burning
- improve reading speed and comprehension
- Normalize blink pattern and frequency
what are the difficulties encountered with artificial tears
- Do not address the underlying inflammation causing Dry Eye
- Do not contain the complex mixture of proteins, mucins or other factors found in healthy tears (just a supprtive mechanism)
- temporary palliative relief
- does not restore normal tear composition
- does not reverse damage to ocualr surface
impoartant factors of artiifical tears
- Preservatives
- Electrolyte composition
- Osmolarity
- Viscosity
artificial tears, solutions:
- most contain hyaluronate: naturally occuring polysaccardie in body found in vitreous/ aqueous humour
- adds viscoelasticity: increased tear stability, reduction fo tear removal, protective effects on corneal epithelium
aritificial tears, gels and ointments
- typically mineral oil and petrolatum
- some have lanolin -> can be irritating
- ointments do not support bacterial growth so they dont require preservatives
- Gels are less viscous then ointments but provide increased retention time
- disadvantage: blurring
lipid based emulsions for artifical tears
- lipid oil-in-water nano-emulsions have been shown to have a long residence time on the tear film,
- reduce the tear evaporation rate
- have a positive effect on the lipid layer
- Nano-emulsions also improve ocular bioavailability of lipophilic or poorly water-soluble drugs
Examples: Systane Balance, Soothe XP, Refresh Optive Advance
preservative vs preservative free artificial tears
- Preservative
- have antimicrobial activity, prolong shelf like by preventing decomposition of active drug
- may be toxic to cornea
- not recommended for extremly dry eye
- Non preservative
- usually more $
- eliminates risk of toxic side effects
- occasionally patient may react to buffer in solution
- come in uni dose vials, multi dose may be mroe difficult to use
- much better for severe dry eye but will get $$
use of warm cmopress for dry eye
*useful for evaporative dry eye -> clogged mebowmian gland
- warm compress is non-invasive, easy method
- poor adherance bc of time and difficulty to get right temp for extended periods of time
- ideal temp is 32-45 C, more obstructed lids should be over 40C
- minimum of 5 min 1d
when counseling touch on
- when to expect relief
- in a simple mild case od dry eye, should notice improvement within a week if using self care strategies
- if improvement not noticed consider other treatment like prescription therapy -> will need a full dry eye assessment
- How long to continue dry eye managemnt
- dry eye = chornic disease, common that patients must continue indefinitely
- can make modifications to theri environment
Cindy, A 28-year-old Asian woman wears contact lenses.
eyes are bloodshot and“burning”.
symptoms are worse in the morning and she has crusty eyelids when she wakes up.
symptoms lessen during the day but become bothersome again at night. She is on no medications and is in good health.
These symptoms have been going on for a number of months. She wants to know if you have any suggestions to help.
5-year-old man with diabetes complains that his eye feels like “there is something stuck in it” and his vision seems to be getting blurrier. He vacations frequently (he lives in Toronto otherwise) where he golfs 2 to 3 times a week and says his symptoms worsen when he’s playing golf, although his vision doesn’t change. He has tried Visine in the past but did not get much improvement from this drop and wants to know if you have any other suggestions?
