Modality of Wear Flashcards
1
Q
What are the classifications of modality of wear?
A
- Daily:
o Only worn during waking hours
o Doesn’t necessarily mean daily disposable this is just type of wear
o Could be daily disposable, could be rigid lens, could be monthly lens - Flexible:
o Mixture of daily wear & occasional night-time wear
o Licensed for both daily and nightly wear
o E.g., mountain climber – maybe only one night every few months when camping that they want night-time wear - Extended Wear (EW):
o Day & night-time wear up to a week with a night off for cleaning - Continuous:
o Day & night-time wear up to a month w/o break during week - RGP:
o As needed replacement – 2-3 years between pairs – if px only wearing RGP for 1 night out a week
o Frequent replacement – regularly scheduled replacement (usually 6/12 or 1 year) – previous pair stored as back up spare pair, unless completely damaged – when px wears lenses more often - Soft:
o Conventional – usually specialist lenses (can be up to 1 year)
o Disposable – up to 1 month
o Daily disposable – every day
2
Q
Define planned and sporadic wear?
A
- Planned – lenses licensed for up to 30 days overnight wear where px plans to sleep in lenses
- Sporadic – lenses licensed for overnight wear but where there is occasional overnight wear, unplanned overnight wear or napping in lenses.
3
Q
What are the replacement schedule soft CLs?
A
- Conventional:
o Part time wearer
o Special parameters – high Rx – send Rx and measurements to company
o RGP lenses
o Special tints
o Compliant – additional cleaning steps - 3 – 6-month Replacement:
o Part-time
o Borderline dry eye – don’t want them on a yearly conventional
o Compliant – additional cleaning steps - 2 – 4-week disposable:
o Full or part-time
o Dry eye
o (Poor compliance) – none of the lenses should have poor compliance but these have better O2 that if px stretches hours too much then good quality lens - 1 day:
o Part/full-time wear
o (Non-compliant) – shown poor compliance with cleaning regimen
o Avoids proper lens care - Always want good compliance but if see hints of poor compliance – minimise risk of complications by going for daily disposable
o If see poor compliance with daily disposable e.g. sleeping in them – then don’t issue the Rx
4
Q
Why should CLs be replaced?
A
- To reduce complications – to minimise risk of complications occurring because lens has been drying out too much or integrity has been compromised so oxygen transmissibility is not good any more
o Lens may have started picking up microbes because it has been worn so much – risk of infection - Simplify cleaning – no protein removing tablets
o Prevents non-compliance - Loss of dimensional stability over time
- Deposits – build up on lenses – proteins, lipids, make-up – comfort decreases
- Improve extended wear comfort (new CLs usually comfier e.g. day 1 comfier than day 14)
5
Q
Why can frequent replacement REDUCE complications?
A
- Complications often caused by CL spoilation
o Discomfort – especially towards end of lens lifespan
o Papillary conjunctivitis
o Infections
o Acute red eye - Therefore, px MUST follow the regimen
6
Q
What are the factors that influence CL spoilation?
A
- Care & maintenance regimen
- Wearing schedule – sticking to it
- Tear chemistry (bad oily tear film from MGD – affectts spoilation of lens – leads to bad quality lipids sticking to lens) & other personal factors e.g. makeup, general hygiene
7
Q
What are factors that influence CL life expectancy?
A
- Thickness – dailies much thinner
- Handling ability – dailies more easy to break and harder to handle
- Environment – v low humidity, high air flow e.g. airplane worker – affects how long CL lasts
- What is a reasonable CL life span?
o Depends on CL material & thickness
8
Q
What are the advantages of frequently replaced CLs?
A
- Reduced lens spoilation
- Reduced risk of infection
- Reduced incidence of papillary conjunctivitis
- Improved comfort
- Safer extended wear – more frequently replaced the lenses, safer they are to be used for EW
- Spare CL availability – e.g. tear a daily disposable then can easily use another
- Low replacement cost
- Reduced time, effort & cost of cleaning
- Favourable px response – lenses are comfier at start of their life
- Easy fitting – mostly one size fits all (w/ some exceptions)
- Easy to change Rx – samples in stock for px to try – if custom lens for px then won’t have them in practice and will have to order them in
- Establishes link to practice – see px for aftercare, solutions, replacement lenses
9
Q
What are the advantages and disadvantages of daily disposable lenses?
A
- Advantages:
o Convenience, no cleaning
o Lower risk of infections than extended wear
o Lower risk of mechanical complications – lenses are v thin – less likely to cause papillary reaction due to mechanical rubbing
o Good for occasional wear – cost efficient as if have monthly lens it is only good until 30 days from opening – it is not 30 wears like dailies (30 individual lenses)
o Good for young px’s – if worried about carrying out cleaning regimen or risk of sleeping in lenses - Disadvantages:
o Limited range of Rx – (improving all time – keep up to date with supplier)
o Cost – (if worn frequently) – some like the convenience
o Handling can be trickier – so thin and don’t have same rigidity as 2-weekly or monthly (could get a px to try a monthly just for I&R to work up confidence)
10
Q
What are the advantages and disadvantages of 2 & 4 weekly lenses?
A
- Advantages:
o Cost efficient for fulltime wear
o Easier handling
o Wider range of Rx’s available – larger range of hyperopic and toric Rxs - Disadvantages:
o Cleaning regimen – new case each month, in date solution – may need to do protein removal
o Reduced comfort at end of lens lifespan (due to deposits on lens)
o Cost if lenses are often lost/damaged
11
Q
What are the advantages and disadvantages of RGP lenses?
A
- Advantages:
o Most cost-efficient of lens types
o If lens gets scratched – lens can be polished
o Excellent quality of vision – more like what get with pair of glasses compared to soft lenses
o Complex Rxs available
o Good tear exchange – RGP floats on tear film & smaller than cornea – depends on type of RGP
o Modifications of lenses possible – e.g. curve can be altered – not always
o Does not cover entire corneal surface – get lots of oxygen in as not blocking oxygen supply – depends on type of RGP
o Various tints available – usually standard handling tint so px can see them and tints to show which lens is for which eye – generally RE = green (R in green) & LE = blue (L in blue) - Disadvantages:
o Adaption time (depends on type of RGP) – requires motivated px
o Foreign bodies – due to way sit on eye, FBs can get underneath & get trapped – get scratch
o Breaking & scratching – stand on lens it will break – scratch like a spec lens
o Precise fitting required – K’s must be correct pick lens based on these K’s
o Risk of loss – RGPs are v small & can’t just grab another one like soft lenses
12
Q
What to consider when choosing a wear modality?
A
- Px requirements
o Safety – modality chosen must be safe for px
o Comfort – put first by px – must also be comfortable for duration of lens life span
o Knowledge/education – px needs to understand the modality chosen and why – and understand modality to know when lens needs changed
E.g. daily disposable needs THROWN OUT daily
o Convenience – if not convenient for px to have cleaning regimen then don’t go down that route – px may accept higher cost of daily disposable because it’s convenient - WORK WITH PX
13
Q
What do you need to consider when comparing daily wear (DW) CLs with Extended Wear (EW) CLs for your patient?
A
- Corneal Status:
o LOOK FOR AT FIRST VISIT
o Any signs of previous over wear or hypoxia?
o If apparently normal
DW
EW
o If signs of compromise apparent
DW only
Or no wear at all
o Look for opacities, distortions to cornea when do keratometry, anything abnormal - Risk Factors:
o These can apply to DW too, but risk heightened with EW
o Corneal oedema
o Loss of corneal sensitivity
o Lens adherence – lens gets stuck when wake up in morning & taking lens out will take epithelium away – if lens is stuck, px puts artificial tears in & waits before trying to get lens out
o Inflammation & infection - Rx Factors:
o Check if available in Rx
o Average thickness of plus or minus lenses – can ↑ corneal oedema – want Px to have best Dk in lens as possible
o O2 demands under specific conditions – e.g. mountain climbing-less oxygen high up
o Corneal changes induced by EW – check K’s regularly to make sure not causing corneal warpage
o Visual acuity changes – e.g. if have oedema - Tear Film:
o Lower threshold for what is acceptable with EW
o Signs of dry eye – overall redness, inflammation of bulbar conj
o Debris
o Excess lipid - Lid Integrity:
o Lower threshold for what’s acceptable for EW
o Prominent papillae &/or follicles – allergy or viral reaction
o Redness of lids & palpebral conj – redness of lid margin usually indicates inflammation
o MGD
o CLAP-C more common in EW – so if px has papillae from hayfever then shows EW might not be best option - Environmental Factors:
o E.g. microbiologist may benefit from EW as less handling of lens & less likelihood of cross contamination
o Exposure to gas, fumes, chemicals & pollutants – don’t want to go for CL as these could be absorbed into CL
o Nature of work – e.g. lots of debris such as carpenter (not good px for RGP)
o Visual demands – does px need high VA? – may need to correct a cyl quite early on - Individual Characteristics:
o Manual dexterity – EW lenses are thicker & tend to have higher modulus so tend to be easier to handle (but so do monthly lenses)
Px can use soft tip tweezers to help them
o Personal preferences
o Previous lens wear experience – if tried EW but woke up in morning & eyes felt dry – find out what px liked/disliked if previously worn lenses so don’t go down same path
14
Q
If the wear time is longer, what does the oxygen or Dk need to be?
A
Longer wearing time, higher the oxygen – if px sleeping in lenses, need highest Dk
15
Q
In which patients are daily disposable lenses better to minimise risk?
A
- Px age (<25, >50)
- Previous Corneal Infiltrative Events (CIEs)
- Bleph/MGD – risk factor for infections – manage bleph/MGD before going ahead with fitting
- History of smoking
- Poor hygiene – not likely to be good, compliant CL wearer
- Certain health conditions e.g. thyroid disease or general poor health
