dry eye and contact lens wear Flashcards
What is the pre lens tear film (PLTF)?
Tear film that sits above the lens and is associated with comfort
Does the pre lens tear film protect against deposits?
Yes
What is the post-lens tear film (PoLTF)? + what is it associated with?
Under the cls, associated with fit + lubrication + movement
What layer of the tear film does a cl sit in?
Aqueous layer
Is a PLTF always present?
No
Why is tear exchange important?
To remove debris + metabolic waste products
What are three effects a cl has on tear film?
- Tear film instability + evaporation (this is sue to wetability)
- Tear film mucins, electrolytes + increased osmolarity
- blinking
What does reduced mucin lead to?
More friction
What will happen to vision due to an unstable tear film?
Vision may fluctuate
Is a higher or lower osmolarity associated with dry eyes?
Higher
If a px has contact lens associated dry eyes (CLDE), what may you see on glands?
- secretions (MGD)
- Expression
- blockages
If a px has contact lens associated dry eyes (CLDE), What should you examine in relation to lids and lashes?
- disease
- lid position
- blink rate
If a px has contact lens associated dry eyes (CLDE), What should you examine in relation to ocular surface?
- staining
- inflammation
- redness
If a px has contact lens associated dry eyes (CLDE), What should you examine in relation to tears?
- tear prism height
- TBUT
- quality
- osmolarity
What are three ways to assess tear volume ?
- phenol red thread test
- schrimer
- tear scope
How do you measure NIBUT?
Using a keratometer
Describe the phenol red thread test.
- thread impregnated with phenol red
- colour changes from yellow to red
- thread hangs 1/3 from lateral canthus
- CANNOT touch cornea
- record after 15s
What result will indicate dry eye with the phenol red thread test?
<9mm
How long does schirmer test take ?
5 mins
What is a disadvantage of the schirmer test?
Strips can feel uncomfortable= stimulate tearing reflex
How does the tearscope work?
- diffuse white reflection over whole cornea
- lipid layer can be assessed
- patterns can be observed
- inserts can be placed to asses corneal distortion + damage
What patterns can be observed with a tear scope? (There are 5)
- open meshwork
- closed meshwork
- wave
- amorphous
- colour fringes
What are another four instruments can assess tears?
- Oculus Keratograph 5M
- Lipview
- InflammaDry
- TearLab- tear osmolarity
What is an Oculus Keratograph 5M?
Topographer
What can Oculus Keratograph 5M assess?
- MGD
- Non-invasive TBUT
- Tear meniscus
- Lipid layeR
What can does Lipview do?
Measures lipid layer + MG imaging
What does InflammaDry do?
Detect inflammatory marker of DED. Takes 10 mins to do
What reading on a TearLab-tear osmolarity will indicate abnormality?
> 300mOsm/L
Why does the lid epithelium change with CLRDE (contact-lens related dry eye)?
Due to friction- this friction is caused a thin tear film between ocular surface and lid wiper
What is lid wiper epitheliopathy?
disruption to the surface epithelium of the lid wiper
What is the lid wiper?
Area of epithelium in contact with the cls and wipes across the cl/eye
How can you observe lid wiper epitheliopathy?
Evert lids + staining with lissamine green
What is lid parallel conjunctival fold (LIPCOF)?
Breakdown in elastic fibres in loose conjunctiva
What causes LIPCOF?
Ageing or mechanical forces between conjunctiva and lower lid
What other signs may you see with LIPCOF?
Tear deficiency and inflammation of the conjunctiva
How is LIPCOF graded?
By number and height of folds
How can LIPCOF be managed?
- change lens type
- change wearing schedule
- manage tear quality issues
- consider rewetting drop
What is MGD?
Blocked meibomian glands
What are two types of dry eye?
Evaporative and aqueous deficient dry eye
Do the two types of dry eye have the same management?
No
What is computer vision syndrome? CVS
prolonged screen use –> reduced blink rate/incomplete blinks –> eye discomfort or visual discomfort
What are some sx someone with CVS may complain of?
- dry eye
- eye strain
- HAs
- blurred vision
- neck and shoulder pain
What is the average blink rate?
12 blinks per min
When reading what may the blink rate drop to?
4.5 blinks per min
What does a reduced blink rate result in?
Tear film is replenished less frequently and evaporates quicker —> leads to ocular discomfort
What are some solutions to a reduced blink rate?
- blinking exercises
- 20-20-20 rule
How should you manage dry eye in practice ?
- lens change
- changes to environment
- eye drops
- lid hygiene
- warm compress
- diet
What changes to environment can you do for dry eyes?
AC not directed in the face in the car as lower humidity = increased evaporation
What does eye drops do for dry eye?
Immediate relief, more viscous agent = better for end of day as it can effect Vision
What must you check with the eye drops?
That they are compatible for cls + preservative free
What advice can you give to someone to manage MGD?
Warm compress for 10 mins twice a day
Before manage dry eye, what must you do?
Identify the cause
In terms of environment, what can contact lens discomfit be increased by?
- low humidity
- increased air flow
- computer use
What diet info can you give to patients with dry eyes?
Take essential fatty acids such as omega 3 and omega 6 rich foods such as avocado, tuna ect
Why should px take essential fatty acids?
The body cannot make them, it will help to enhance the lipid layer by reducing evaporation
Can too much consumption of omega 6 negate the effects of omega 3?
Yes- balance is key
Should you recommend ur px to drink more water for dry eyes?
You can do but few studies have looked into this , you can tell them to limit alcohol and caffeine consumption
What is viscosity?
Fluids internal resistance to flow
What does a high viscous agent aim to do?
- increase retention time
- reduce friction
- soothe irritated membranes
What lid hygiene tips can you give to someone with dry eyes and bleph?
- clean lid margins x2 a day while condition bad and then can be decreased to x1 a day
- clean with lid cleaning solution
- avoid makeup on eyes
How would you find out which dry eye they?
Through h&s + anterior eye assessment
Should you follow up a dry eye px ?
Yes- book a follow up or phone call
