SCL Fitting 1 Flashcards
On what basis are RGPs replaced?
Replacement every 1-3 years or earlier if scratched
On what basis are soft contact lenses replaced?
Depending on the type they are:
– Daily disposables (DW)
– Bi-weekly or Monthly disposables (EW)
[EW- extended wear]
What is a daily disposible lens?
FDA definition: a lens replaced after each use (i.e. remove and discard)
What are examples of daily soft contact lenses?
- Acuvue 1-Day Moist
- Dailies Aqua Comfort Plus
- Biotrue ONEday
- Proclear 1 Day
What are examples of Bi-weekly replacement soft contact lenses?
- Acuvue 2
- Acuvue Oasys
- Avaira
What are examples of monthly soft contact lenses?
- Air Optix Aqua
- Proclear, Frequency 55
- Biofinity
- Air Optix Night & Day
- Purevision 2
In the UK, which is the most popular type of contact lens, SCL or RGP?
SCL
What factors are driving the growth of the SCL market?
Growing rate of myopia
Growing Geriatric population
Increasing preference fo contact lenses
What factors are hindering the growth of the SCL market?
Unregulated online sales
Regulatory barriers concerning contact lens sale
What was the first soft hydrogel contact lens material?
HEMA (in 1970).
[It continues to be the monomer most often utilised]
Is HEMA very stable or unstable of a material?
Very stable - variations in temperature, ph, etc have vewry little effect on it
Is HEMA a comfortable lens material?
Yes
[It contains water and transports O2]
True or false- HEMA has good wetability
True
True or False- Silicone hydrogels allow for less oxygen transmission than HEMA based contact lenses
False - SiH CLs allow for more oxygen transmission
Which are more expensive HEMA (hydrogel) Lenses or SiH (Silicone hydrogel) lenses?
Silicone Hydrogel lenses
How does wetability affect comfort?
Wetability aides the closure of the lid over the lens thereby improving comfort and preventing changes to the papillary surface (of inner eyelid).
A very wetable surface creates an even stable tearfilm optimsing comfort, visual acuity and resistance against deposits.
What does it mean to have no net increase in the amount of contact lens wearers?
It means that for every new contact lens wearer there is an old contact lens wearer that discontinues use
What is a material’s modulus?
A value that expresses a material’s ability to keep its shape against stress, and resistance to deformation.
What are the properties of materials with a higher modulus?
They are stiffer, resist deformation, hold their shape better, are easier to handle and may provide better VA.
[Stiffer lenses though may have adverse effects as they cause an edge lift and can cause a SEAL, they can cause mucin balls or CLPC (Contact Lens Papillary Conjunctivitis)]
What is the relationship between sleeping in contact lenses and eye infections?
Sleeping in contact lenses makes you 8 times as likely to develop an eye infection
What are the strict rules regarding contact lenses and water?
Don’t ever bath, shower or swim in contact lenses!
List some indications for fitting Soft Contact Lenses

What are the main contra-indications for use of Soft Contact lenses?
Highlighted in red + pregnancy

What are the two possible care regimes for soft contact lenses?
and what are the advantages of both?
You can use Multipurpose solutions or Hydrogen Peroxide
Multipurpose solutions:
- These are Simple and convenient
- And can be used for Cleaning, disinfecting, and storing
- Method of use is to Clean, rub, rinse and store in (for min 4-6 hrs)
Hydrogen peroxide:
- These are a Metallic disc in case or tablet to neutralise the disinfectant before wear
- Px cannot have adverse reaction to preservatives
- Gold standard?



