Contact lens and dry eye management Flashcards
what is the incidence of dry eye in contact lens wearers
52.7%
what is the incidence of dry eye in the general population
14-33%
what time of day do contact lens wearers tend to get dry eyes
at the end of the day with soft contact lenses when their lenses have dried out
what structure of the eye does a contact lens divide, and what are these divided structures called
- it divides the pre corneal tear film into the:
Prelens tear film (PLTF) and the post-lens tear film (PoLTF)
what is the pre lens tear film (PLTF) associated with
comfort-needs to protect lens from drying or getting deposits
what is the post lens tear film associated with
lens fit and movement
what will happen to which ocular structure if a contact lens dries out in the eye
it will scratch the cornea when blinking
when should you assess the tear film and what should you see in slit lamp
- assess the tear film before and after putting the lens in
- on slit lamp, do specular reflection to check the tear film for purkinje image 1 with the lens in
which layer of the tear film does the contact lens sit on
the aqueous layer of the teat film
Lipid layer __________ and
sometimes _________ in PLTF
Lipid layer thinner and
sometimes absent in PLTF
as a result of a thinner or sometimes non existent lipid layer in the pre lens tear film, what happens to RGP and soft contact lenses
- RGP - lipid layer is almost non-existent therefore get deposits on the lens as theres no tears to wash them away
- SCL - get spots on the lens
what does the post lens tear film help with, and what function is important for a post lens tear film and why
- helps posterior lens lubrication - Tears must not be static, tear exchange is important for removal of tear debris and metabolic by products
which type of lens does RGP lenses have more tear mixing than
hydrogel lenses
list 4 effects that contact lenses have on the tear film
- Changes in tear production?
- Tear film instability and evaporation
– Related to lipid layer and initial tear film thickness
– Visual acuity may fluctuate - Effect on tear film mucins, electrolytes and increased osmolarity
– Reduced mucin, increased friction
– Higher osmolarity associated with dry eyes - blinking
explain the 2 effects of tear film instability caused by contact lens wear
- Related to lipid layer and initial tear film thickness
= the lens dehydrates and dry sports are formed on the lens - Visual acuity may fluctuate
as well as the visual acuity which may fluctuate, what other acuity is also affected by contact lens use
contrast sensitivity also declines whilst wearing the contact lenses
explain the 2 effects on tear film mucins, electrolytes and
increased osmolarity caused by contact lens wear
– Reduced mucin = increased friction
– Higher osmolarity associated with dry eyes, as this reflects the concentration of proteins and electrolytes
what does a higher osmolarity in the tears reflect
the concentration of proteins and electrolytes in the tears
how is the effect of contact lens on the tear film related to blinking
initially the patient blinks a lot (reflex tearing), but afterwards they start to blink less, however this doesn’t stop the lens from dehydrating
reflex tearing doesn’t….
stop the lens from dehydrating
list the 5 different factors of the multifactorial condition of contact lens related dry eye
- patient characteristics
- lens material
- environment
- lens fitting
- lens solution
name 2 clinical ocular signs of contact lens related dry eye (CLDE)
- Lid wiper epitheliopathy (LWE)
- Lid parallel conjunctival folds (LIPCOF)
where is and what is the job of the lid wiper
- the portion of the marginal conjunctiva of the upper eyelid
- its job is to wipe the ocular surface during blinking
what happens during lid wiper epitheliopathy and what is the consequence
- The dry anterior surface of lens rubs against the underside
of eyelids, particularly the area near the eyelid margin - Tear film thickness too thin to separate ocular surface
and lid wiper
As a consequence, this causes an alteration in epithelium due to friction
what may you do to look for lid wiper epitheliopathy
Staining:
- May stain with NaFl, but more so with lissamine green
- Will need to evert lids
which eyelids is the staining found from lid wiper epitheliopathy most commonly found
Usually staining on upper lids, but can also affect lower lid
although lid wiper epitheliopathy may be asymptomatic, name 3 symptoms that can occur
- May have increased lens awareness
- Irritation on blinking
- Reduced wear time
as the patient blinks, they will feel the lens rubbing as the pre lens tear film is not thick enough
list the 4 signs of lid parallel conjunctival folds (LIPCOF)
- Breakdown/decrease in elastic fibres in the loose conjunctiva
- Conjunctival looseness
- Ageing or mechanical forces
between conjunctiva and lower lid - Tear deficiency and inflammation of the conjunctiva
what happens as a result of ageing or mechanical forces
between conjunctiva and lower lid and what will a patient who has this also have
- it is conjunctival looseness and folding of the conjunctiva
- if the patient has this, then they will have lid wiper epitheliopathy
what is lid parallel conjunctival folds (LIPCOF) graded according to
the number and the height of the folds
describe grade 1 of lid parallel conjunctiva folds (LIPCOF)
one permanent and clear parallel fold
describe grade 2 of lid parallel conjunctiva folds (LIPCOF)
two permanent and clear parallel folds which are normally less than 0.2mm
describe grade 3 of lid parallel conjunctiva folds (LIPCOF)
more than 2 permanent and clear parallel folds normally > 0.2mm
list 3 things that can be done to manage lid parallel conjunctiva folds (LIPCOF)
- Change lens type or wearing schedule
- Manage any tear quality issues
- Consider rewetting drops
what is the condition called for patients who have a lifestyle of prolonged computer, tablet or phone use, which can cause dry eyes
computer vision syndrome (CVS)
list 5 symptoms of computer vision syndrome (CVS)
eye discomfort and visual problems including:
- Dry eyes…related to blinking
- Eyestrain
- Headaches
- Blurred vision
- Neck and shoulder pain
what is value for resting blink rate
12x a minute
when may blink rate change depending on
- activity, on cognitive or emotional function
- some diseases and medication
what can cause a blink rate to increase
when engaged in conversation
what can cause blink rate to decrease and to what value can this decrease down to
when focussing on a specific visual task
can drop to an average of 4.5x per min when reading
what diseases can blink rate be affected by
- parkinson’s
and - schizophrenia
what does a reduced blink rate mean for the tear film
it is replenished less frequently and evaporates quicker causing ocular discomfort
what is computer vision syndrome associated with
a reduced blink rate
by how much does a patient with computer vision syndrome blink less
by 60% less blinking
as well as reduced blink rate in computer vision syndrome, what is also reduced
the completeness of a blink
what is described as a full/complete blink
when the top lid touches the bottom lid
what is increased with computer vision syndrome
increased teat break up time
list 5 things that can be done for managing the symptoms of dry eye
- Lens changes
- Changes to environment
- Eye drops: lubricants, lipid specific products
- Lid hygiene: lid cleansing, heat
- Diet
what should you start off with in order to diagnose/manage your patient with contact lens related dry eye
a thorough history and symptoms
list 3 things/questions a thorough history and symptoms should consist of
- Use of dry eye questionnaires
- Is wear time all comfortable wear time?
- When do symptoms begin/end?
How often do symptoms occur?
Are they present even without
the lens? (work out if its the lens or the eye thats the cause)
list 7 ideal characteristics of a contact lens which has the minimum effect of causing dry eye
- Good hydration
- Low surface friction
- High wettability
- Low levels of deposition
- DK/t
- Fit and lens design
- Replacement frequency
how do you check that a lens has a low surface friction
it is measured by the coefficient or friction
the lens should be smooth when blinking
what do you want to avoid with a lens design in order to avoid dry eyes
don’t want the lens to be too steep as we don’t want the edges to pinch in
what 7 causative factors requires a management of the patients environment as it increases contact lens discomfort
- Low humidity
- Increased airflow
- Computer use
- Temperature
- Allergies such as hay fever, pollen, dust and pets
- Air pollution
- Smoking, which can build up on reusable lenses
list the 5 ideal features of eye drops
- Immediate relief
- Prolonged effect
- Non-toxic
- Doesn’t blur vision
- Inexpensive
what 3 things must you check before prescribing eye drops to a contact lens dry eye patient
- Check compatibility with contact lenses - Preservative free ? - Ensure no other cause of symptoms…e.g. poor lens fit
what is viscosity
the measurement of a fluid’s internal resistance to flow
what does a higher artificial teat viscosity means for tear retention time
tear retention time is increased and might help protect the ocular surface
what are the 3 aims of viscosity agents
- Aim is to try and increase
retention time - Reduce friction
- Soothe irritated membranes
what type of ocular lubricants is reserved for more severe dry eye
gels and ointments
what is associated with the use of ointments
blurred vision
what are the 3 rules of lubricating ointments
- avoid with CL wearers
- for use at night
- note recent product recall
Increased ___________ and
____________ indicates
dry eye
Increased osmolarity and
inflammation indicates
dry eye
Some say osmolarity
which ________ osmolarity of normal tears is ______, others suggest ___________ artificial tears are _______
Some say osmolarity which mimics osmolarity of normal tears is ideal, others suggest hypoosmolar artificial tears
are better
what do hypotonic artificial tears do to the tears
reduces the osmolarity of the tears and also reduces salt levels
Products which mimic the _________ composition of _______ tears are available
Products which mimic the
electrolyte composition of natural
tears are available
which 2 electrolytes seem to be important for tears
- potassium
- bicarbonate
what is electrolyte balance in the tears important for
the maintenance of conjunctival goblet cells
what is the property of conjunctival goblet cells
to act as a natural lubricant
what 4 things must you do before issuing someone with lubricating eye drops
- Spend time discussing condition with patient and explaining management plan
- Demonstrate use (do not just issue product samples)
- Instruct how often patient should use drops
- Book a follow-up/review: e.g. after a month, to make sure what we have prescribed works
what are the instructions for maintaining lid hygiene
- Diluted baby shampoo, sodium bicarbonate solution or lid cleaning solution with a cotton bud
- Clean lid margins (not beyond the mucocutaneous junction)
- 2x daily; reduce to 1x daily as condition improves
- Use firm pressure with cotton bud to express glands
- Warm compresses to loosen collarettes and crusts
- Avoid use of cosmetics, especially eye liner and mascara
what three things can be used for lid hygiene
- diluted baby shampoo
- sodium bicarbonate solution
- lid cleaning solution
what is the aim of warm compress therapy
Aim of therapy is to melt the meibum to allow it to be expressed and to prevent obstruction of the terminal ducts
what should be monitored when doing warm compresses
temperature
you don’t want to burn the eyes, you just want the temperature to be warm enough to melt the meibum within the glands
name a heating device that can be used as a warm compress therapy
the Eyebag - which is a silk and cotton device which is filled with flaxseed (linseed)
how long does a Eyebag take to heat up and how does the heat last for
- 30-40 seconds to heat
- 10 minutes heat is retained
what is required in our diet that our body cannot make itself
essential fatty acids
which have to come from our diet
what are essential fatty acids understood to enhance
the lipid layer of our tear film, reducing evaporation
name 2 essential fatty acids and what each of their properties are and hence the implications this may have
Omega 3 – anti-inflammatory properties
Omega 6 - pro-inflammatory properties?
Too much consumption of omega 6 may negate the effects of omega 3
what 2 types of liquid will generally dehydrate the body
caffeine and alcohol
why is drinking water a weak management plan for dry eyes
because there is not a big enough study to prove that it’s effects work
list all the 7 possible management routes that can be taken to treat dry eyes
- environment changes
- eye drops/gels/ointments
- osmolarity agents
- lid hygiene/scrubs
- warm compresses/heating devices
- essential fatty acids in the diet
- drinking water?
