Dry Eye (DE) in CL Wear

Question 1

Describe the tear film?

Answer 1

• Complete tear film is essential for:
  o Antibacterial properties – to fight infection
  o Transporting nutrients to cornea – cornea is avascular so needs nutrients from somewhere
  o Optical performance of eye – if not good tear film then not smooth refraction of light into eye & so blurred vision is symptom of DE – if tear film is damaged then can affect vision overall
  o Successful CL wear
• Dry eye is due to disorder or disturbance of tear film

Question 2

Describe the structure of the tear film?

Answer 2

• Outer oily layer
  o Produced by meibomian glands (if have MGD it is lipid layer you lack leading to ↑ evaporation)
  o Smoothes tear surface and decreases evaporation
• Aqueous (Watery large middle) layer
  o Produced by lacrimal gland
  o Carries nutrients & oxygen to cornea
  o Washes away particles & irritants
• Inner mucous layer
  o Produced by conjunctiva (in particular goblet cells)
  o Provides protection & ensures eye remains moist
  o Vital for stability of tear film (vital in ensuring tear film remains on)
   Now being described more as a mucin gradient through the tear film

Question 3

What is dry eye disease (DED)?

Answer 3

• Complex group of conditions
• Characterised by a dysfunction of one or more of components of tear film
• Multifactorial – can be multiple things causing it
• Types:
  o Evaporative (e.g. due to MGD)
  o Aqueous deficient (e.g. due to age)
  o Mixed – both of above
   Aqueous deficient px has reduced production of tears
   Evaporative px has increased evaporation with normal production of tears

Question 4

What are the symptoms of Dry Eye Disease (DED)?

Answer 4

Range of symptoms from px to px is vast
* Grittiness
* FB sensation
* Lacrimation – watery – evaporative DE & eye producing too much aqueous
* Itching – especially if there is bleph
* Blurred vision
* Redness
* Photophobia (usually not severe) – if lots of corneal involvement

Question 5

What are the signs of Dry Eye Disease (DED)?

Answer 5

• Conjunctival hyperaemia – grade on record card
• Reduced TBUT
• Corneal & conj staining – NaFl (for corneal) (or lissamine green with red filter – for conjunctival)
• Reduced tear volume – measure tear meniscus height or Schirmer test
• Signs of anterior bleph/MGD

Question 6

Describe Tear Film Break Up (TBUT)?

Answer 6

• Initially tear film thins by evaporation
• Some lipid molecules are then attracted to mucin layer (top layer attracted to base layer) & begin to migrate to this layer
• When mucin layer is fully contaminated by lipid, mucin becomes hydrophobic & tear film ruptures
  Looking for 1st point of break up (when 1st goes dark)

Question 7

What are the common causes of Dry Eye Disease (DED) in CL wear?

Answer 7

Common condition
Blinking:
* Decrease blink efficiency:
o Frequency
o Completeness
Lens Surface:
* Increased deposits
* Decreased wettability
Material Itself Drying Out:
* Material dehydration:
o Fitting Changes
o Epithelial Staining

Question 8

What do you need to rule out in CLs and dryness?

Answer 8

• Need to rule out:
  o Poor fitting
  o Manufacturing problems
  ^Look for these whit lens still in eye

Question 9

What are the effects of CLs on Tear Film?

Answer 9

• Destabilisation
• ↓ TBUT – due to change in stability
• ↓ tear volume (tears may be insufficient to cover CLs adequately)
• ↓ lipid layer
• Stagnation of the post-lens tear film – not getting tear turnover that would expect – more vulnerable to infection
• ↑ tear evaporation rate (esp. SCLs)

Question 10

What are the effects of CLs on Lids?

Answer 10

• Altered tear menisci - & altered tear meniscus height
• ↑ blinking (to resurface the eye)
• Incomplete blink amplitude
• Lid conformance to the eye may be impossible → leads to 3 & 9 staining (RGPs)

Question 11

What are the effects of soft CLs on Tear Film?

Answer 11

• ↑ evaporation
• ↓ tear film stability (< 6 sec not uncommon)
• After 6 months of soft CL wear:
  o ↓break up time by 3 sec
  o ↑DED incidence from 28% (before soft CLs) to 68% (after soft CLs)

Question 12

What are the effects of RGPs on Tear Film?

Answer 12

• Lids unable to conform to shape of lens-anterior eye
  o 3&9 staining
  o Lens adherence
• Post-lens tear film stagnation by restricting tear exchange
• Tear film continuity more difficult to maintain, especially if:
  o ↑ edge clearance (seen on flat lens)
  o Thicker edges
  o ↑ lens mobility (seen on flat lens)
• ↑ foreign bodies & contaminants move and destabilise tear film – not getting active tear flow below RGP

Question 13

Describe wearer selection with CLs and DED?

Answer 13

• Eliminate:
  o those with marked tear instability
  o the deposit prone – may not know this before CLs
  o NIBUT < 10 seconds
   Be wary of NIBUT 10 - 20 seconds
   Happy with those with NIBUT > 20 seconds
  o Significant blepharitis – at least until managed as it increases risk of infection
• If someone is borderline DE before start CL wear then follow them up often and give them appropriate advice re wear time & selecting a good lens

Question 14

Describe the CL wear modality and DED?

Answer 14

• Generally, EW contra-indicated unless ‘bandage lens’ effect is required
• Regular replacement programme desirable
• Daily lens disposal not confirmed to be better – limit the number of hours when have DE problem

Question 15

What is the management of DED in soft CLs?

Answer 15

• Don’t change everything at once as then won’t know which thing has worked
• Aim is to ↓ tear film evaporation
  o Material (ionic if replaced very regularly, otherwise non-ionic)
   Ionic materials have a -vely charged surface & therefore may attract +vely charged proteins in tear film (Purevision, 1-day Acuvue Moist, Freshlook)
   Non-ionic hydrogels are treated to reduce this -ve surface charge & therefore may be less prone to attract protein deposits (Oasys, Air Optix, Biofinity, Avaira, Proclear, Focus Daillies)
• Most modern soft CLs are non-ionic
  o Lens thickness (thicker)
  o Water content (low, but px-dependent, high water should be tried as a last resort for comfort if px is only going to be wearing lenses for a few hours)
   Low water content won’t draw as much water out of tear film to maintain its integrity
  o Wearing schedule (minimal) – may have to be quite strict with this if someone has DE
• Lubrication (unpreserved) – or say on bottle suitable to use with CLs
• Preservative-free lens care products
• Refit with RGP lenses if unsuccessful
• ↑ replacement frequently to:
  o ↓ deposits
  o ↑ TBUT (& improve tear stability)
   E.g. if px is on monthly try a 2-weekly

Question 16

What is the management of DED in RGPs?

Answer 16

• Need to minimise 3&9 staining
  o Centration (higher riding)
  o Total diameter (larger)
  o Edge thickness (minimal)
• N.B. rigid lenses are better for DED because:
  o ↑ tear exchange
  o No evaporation staining (as would get with soft CLs)

Question 17

What do you need to think about when choosing CL care products?

Answer 17

• Avoid using products containing older generation preservatives/disinfectants (these all are absorbed by CL):
  o Thimerosal
  o Chlorhexidine
  o Benzalkonium chloride (BAK)
• Choose those with lubricating/re-wetting function incorporated

Question 18

Describe re-wetting drops (lubrication) in CLs (& DED)?

Answer 18

• Benefits last only up to 5mins
  o Tear film stabilised for 5 mins
  o No effect on lens hydration – just adding extra lubrication, extra tear volume to ocular surface which gives stabilisation
• Use unpreserved products where possible
  o Usually preferred by users/pxs
  o BAK etc injuries to cornea
  o Long-term effects of preservatives on cornea (wide-spread punctate staining)
• Choice of drops:
  o Drop must be suitable for CL wear and go for modern preservatives or preservative free
  o Not always much difference between the drops – px preference
   Bausch & Lomb Biotrue Rewetting drops
   Blink contact soothing eye drops
   Allergan Refresh Contacts
   Hylo-fresh Lubricating eye drops
   Alcon Systane Contacts Soothing Drops
   Opti-free Replenish Rewetting drops

Question 19

Describe management of DED in CL wear?

Answer 19

• If CL wearer develops a dry eye or reports sxs of eye irritation or discomfort:
  o Assess case-by-case
   Is CL wear to cease? – assess the damage, if the CLs pose to great a risk of infection if the ocular surface is damaged then cease
   Will comfort drops suffice? – if the ocular surface damage is not too bad – will need to use these regularly (every couple of hours) – discuss with px
   Should a different lens/wear modality/schedule be trialled? – try SiHy, if on EW then change them, cut number of hours
   Is eye ‘marginally dry’? – does the dryness only occur when they’ve been at computer for 8 hours? Or when they’re at work in air-conditioned environment? – ASK MORE Q’s
   What tests are appropriate? – TBUT, tear meniscus height, corneal & conj staining, look closely at lids (bleph, MGD – may not be the CL)
  o Regardless, management is difficult – keep pxs expectations in check
   DE is often chronic and lifelong condition
• If ocular surface is compromised – cease/pause wear – DO NOT WANT ACANTHOEMEBA OR MARGINAL KERATITIS
• Soft CLs pose a greater risk for DE and for infection
• What CL to use?
  o Element of trial & error to this – not one answer
  o If px has bit of DE at initial fit then do not go for EW

Question 20

How do you prevent problems of DED in CL wear?

Answer 20

• Identifying borderline CL candidates at initial visit (w/ NaFl)
  o Predictive testing – break up time
  o History – work, hobbies, previous problems, meds (antihistamine, beta blockers, contraceptive pill cause DE)
• Treating conditions in advance
  o MGD
  o Bleph - anterior
• Tear supplements from beginning
• Punctal plugs (prevent tear drainage so then more stagnant tears on surface – could lead to infections with CLs – literature unclear)
• Adapting to circumstances
  o Px expectations
  o Environmental changes – if they sit under AC vent at work see if they can move desks, avoiding AC in car where possible, moving screen lower to decrease palpebral aperture, wrap around sunglasses
• Lens replacement
  o Optimal schedule
• Dry eye pxs should have reduced CL wearing time expectations
• Consider:
  o Part-time wear &/or
   Shorter wearing periods
  o CL wear as being need-driven rather than routine – doing this from beginning sets the px’s expectations

Question 21

Describe existing Dry Eye & CL wear prognosis?

Answer 21

• Does DE contra-indicate CL wear?
  o DE may increase risks
   Risk of infection
   Due to change in tear proteins (↓ antibacterial agents)
  o Risk of lens fitting problems
   Decentration – too much movement
   Excessive movement
   Adherence due to DE – can take off epithelium if px does not wait for lens to be mobile again before taking them out
• Risk of symptoms:
  o Irritation
  o Photophobia
  o ↓ wearing time
• Px counselling:
  o Possible consequences of CL wear
  o Importance of compliance – px must follow your instructions
   Do not hesitate to not issue a CL Rx if px is not being compliant
  o Expectations of lens wear