Week 5 - Modality of Wear Flashcards
Classification of different contact lenses by wearing schedule:
• Daily: Only worn during waking hours
• Flexible: mixture if daily wear and occasional night time wear
• Extended: Day and night time wear up to a week with a night off for cleaning
• Continuous: Day and night time wear up to a month
2021 Classification update stated what about planned and sporadic wear?
• Planned wear: Up to 30 days overnight where were px plans to sleep c lenses
• Sporadic lenses: overnight wear but where there is occasional overnight wear
What are the use cases for Conventional and daily wear?
Conventional
•Part time wearer
• Special parameters
• RGP lenses
• Special tints
1 day
• Part/full-time wear
• Non-compliant
• Avoids proper lens care
What are the use cases for 2-4week and 3-6month lenses?
2 - 4 Week Disposable
• Full or part-time wear
• Dry eye
• Poor compliance
3 - 6 month Replacement
• Part-time
• Borderline dry eye
• Compliant
What are the classifications for RGP’s and Soft lenses?
• RGP:
- As needed - can be 2-3 years
- Frequent replacement - regularly scheduled replacement (usually 6/12 or 1 year)
• Soft:
- Conventional - usually specialist lenses (can be up to 1 year)
- Disposable - up to 1 month
- Daily disposable - every day
Why should CLs be replaced?
• To reduce complications
• Simplifying cleaning - no protein removing tables
- Can be used for non-compliant Pxs
• Loss of dimensional stability over time
• Deposits
• Improve EW comfort (new CLs usually comfier)
Why can frequent replacement reduce complications?
• Complications often caused by CL spoliation
- Discomfort
- Papillary conjunctivitis
- Infections
- Acute red eye
What factors influence CL spoliation?
• Care and maintenance regime
• Wearing schedule
• Tear chemistry and other personal factors
e.g make up
What influences on CL life expectancy?
• Thickness
• Handling ability
• Environment
What are the many advantages of frequently replaced CLs?
• Reduced lens spoilation
• Reduced risk of infection
• Reduced incidence of papillary conjunctivitis
• Improved comfort
• Safer extended wear
• Spare CL availability
• Low replacement cost
• Reduced time, effort and cost of cleaning
• Favourable patient response
• Easy fitting
• Easy to change Rx
• Establishes link to practice
What are the advantages to daily disposables?
l
- Convenience, no cleaning
- Lower risk of infections than EW
- Lower risk of mechanical complications
- Good for occasional wear (cost efficient)
- Good for young Px’s
What are daily disposable’s disadvantages?
- Limited range of Rx (this is improving all the time)
- Cost (if worn frequently)
- Handling can be trickier - why?
What are the advantages to 2 and 4 weekly?
- Cost efficient for FT wear
- Easier handling
-Wider range of Rx’s available
What are the disadvantages to 2 and 4 weekly lenses?
-Cleaning regime
- Reduced comfort at end of lens lifespan (deposits on lens)
- Cost if lenses are often lost/damaged
What are some important points about SCL> 1 Month?
• 3, 6 or 12 months
• Can increase chance of infection
• Protein removers likely
• Reduced comfort can occur
• Not commonly used (1% in USA 2015)
• Specialised custom fits
• Expensive if lost but generally cost efficient
When would you use RGP lenses?
• High Rx (sphere and/or cyl)
• Irregular corneal curvature
• Ortho-K lenses
• Can be both part time or full time wear
Advantages to RGP lenses?
- Most cost efficient lens type
- Excellent quality of vision
- Complex Rx’s available
- Good tear exchange (depends on type of RGP)
- Modifications of lenses possible
- Does not cover entire corneal surface (depends on type
RGP) - Various tints available
Disadvantages to RGP lenses?
- Adaption time (again, depends on type of RGP)
- Foreign bodies
- Breaking and scratching
- Precise fitting required
- Risk of loss
What patient requirements need to be considered when choosing a wear modality?
Patient requirements
• Safety
• Comfort
• Knowledge/education
• Convenience
What different types of frequency of wear are there?
• Full time (6-7days)
• Part time (2-3 days)
• Social occasions only
• Sport
• Work hours only
What Rx issues can pose a problem to contact lenses?
• Myopia
• Hyperopia
• Astigmatism
• Aphakia
• Anisometropia
• Keratoconus
How does cost influence lens replacement schedules?
• RGP lenses are more cost effective
• Lens cost vs lens care cost
Why is convince and practicality important?
• Frequent lens handling
• Propensity to lose lenses
• Frequent travelers
How can frequent lens replacement affect patient management?
• Produces fewer complications
• Reduces chair time
• Prevents deposit build up
What should a patient be counselled on with contact lenses?
• Maintaining wear schedule
• Cleaning instructions
• Compliance:
- solutions
- different lens requirements
What 7 considerations need to be considered when considering Daily vs Extended wear lenses?
• Corneal status - any signs of previous over wear or hypoxia?
• Risk factors
• RX
• Tear film
• Lid integrity
• Environmental factors
• Individual characteristics
Why is corneal status considered?
Corneal Status
• If apparently normal
- DW/ EW viable
• If signs of compromise apparent
- DW only
- Or no wear at all
What are risk factors considered?
• Corneal oedema
• Loss of corneal sensitivity
• Lens adherence
• Inflammation and infection
Why is prescription factors considered?
• Average thickness of plus or minus lenses (can increase corneal oedema)
• Oxygen demands under specific conditions
• Corneal changes induced by EW
• Visual acuity changes
Why is tear film considered?
• Signs of dry eye
• Debris
• Excess lipid
What lid integrity is considered?
• Prominent papillae and/or follicles
• Redness
• MGD
May be better prognosis with different lenses, i.e RGP
What environmental factors are considered?
• Exposure to gas, fumes, chemicals, & pollutants
• Nature of work
• Visual demands
What individual characteristics are considered?
• Manual dexterity
• Personal preferences
• Previous lens wear experience
Take home message about wear time…
• The longer the wearing time the higher the oxygen requirement
- E.g. Daily Aqua Comfort Plus has a dK of 26
Air Optix Night & Day has a dK of 140
What are the CLEAR reported risk factors for corneal infiltrates?
In all cases, daily disposables might be better option to minimise risk
• Patient age (<25; >50)
• Previous CIEs
• Bleph/MGD
• History of smoking
• Poor hygiene
• Certain health conditions e.g. thyroid disease or general poor health
