Dry eye

Question 1

What keeps healthy eye comfortable and wet

Answer 1

tear film

• > lipid, aqueous and mucus layer
• > dry eye disease sees breakdown of squaeous and lipid layers

Question 2

what is the prevalence of DED

Answer 2

• 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

Question 3

what are the risk factors for DED

Answer 3

• 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

Question 4

what is the impact of dry eye disease on quality of life

Answer 4

• 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

Question 5

what is current definition of dry eye disease

Answer 5

• 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.”

Question 6

what is the main unit that is disrupted in dry eye disease

Answer 6

• lacrimal functional unit

Question 7

what are the parts of the lacrimal functional unit

Answer 7

• 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

Question 8

what is the role of tear film

Answer 8

• nutrition O2
• Blink
• imp for contact lens wear
• lubrication
• vision
• lid margin (inflammation here will cause there to be inadequate secretion of lipid layer

Question 9

what are teh four components of the vicious circle of dry eye disease

Answer 9

1. Tear film hyper osmolarity: environmental factors associated with dry eye

*ow humidity, wind, heat, inadequate blinking, smoking cigs

2. 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

3. Surface damage (cellular level)
4. Inflammatory mediators: factors assocaited with aq deficient dry eye

*aging, low androgens, autoimmune reposnse, lactimal obsturction

*management of dry eye targets there 4 components

Question 10

What are the main types of dry eye diseae classification

Answer 10

• 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

Question 11

what are the symptoms of dry eye disease

Answer 11

– 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

Question 12

how is the sevarity fo dry eye graded

Answer 12

Mild: good secretions

Moderate: plugging of gland, vascularization of eyelid margins

Severe: blocked meibomian ducts (thick secretions)

Question 13

the msot common form of dry eye disease is

Answer 13

evaporative

Question 14

what are goals of therapy for dry eye disease

Answer 14

• improve patients ocular comfort and quality of life
• return ocular surface and tear film to normal homeostatic state

Question 15

what are the types of maintenance treatment for dry eye disease

Answer 15

• 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

Question 16

what are the types of maintenance treatment for chronic (inflammatory) dry eye

Answer 16

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)

Question 17

primary self care for evaproative or mixed DED

Answer 17

• 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

Question 18

what makes a good artificial tear

Answer 18

Drops should:
- Reduce burning

• improve reading speed and comprehension
• Normalize blink pattern and frequency

Question 19

what are the difficulties encountered with artificial tears

Answer 19

• 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

Question 20

impoartant factors of artiifical tears

Answer 20

1. Preservatives
2. Electrolyte composition
3. Osmolarity
4. Viscosity

Question 21

artificial tears, solutions:

Answer 21

• 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

Question 22

aritificial tears, gels and ointments

Answer 22

• 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

Question 23

lipid based emulsions for artifical tears

Answer 23

• 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

Question 24

preservative vs preservative free artificial tears

Answer 24

• 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 $$

Question 25

use of warm cmopress for dry eye

Answer 25

*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

Question 26

when counseling touch on

Answer 26

1. 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
2. How long to continue dry eye managemnt
   
   1. dry eye = chornic disease, common that patients must continue indefinitely
3. can make modifications to theri environment

Question 27

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.

Answer 27

Question 28

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?

Answer 28