Competency 5.1.2 Flashcards
Needs of a SCL Teach
- Clear instructions of lens insertion and removal
- Clear instructions on hand hygiene when handling lenses/cases
- Observation of lens handling and I&R
- Explain cannot sleep, shower or swim in lenses
- Explain cannot mix lenses in any way with water
- Advised to build up wear time initially
- Advised to remove lenses if any pain/redness/discharge and seek help (us or A&E)
- Provide information booklet
- If daily:
- Do not reuse lenses
- If monthly:
- Cannot be used for more than month after opening
- Advised on care regime
- Replace case and solution every 3 months
SCL Edge Designs
- Silicone hydrogel lenses can have thinner edge which improves comfort but may result in conjunctival staining
- Known as knife edge design
Hydrogel as a SCL Material
- Very flexible material due to high water content which results in high comfort due to low modulus
- Oxygen transmissibility is dependent on the water content of the lens
- They become dehydrated in long periods of wear and lens becomes tighter on the eye
- Poorer wettability
What is Example of Hydrogel Material
- poly-HEMA
- Dailies AquaComfort plus (Vitrea)
Advantages of Hydrogel Lenses
- Flexible
- Affordable
- Good initial comfort
- Thinner lens
Disadvantages of Hydrogel Lenses
- Low oxygen permeability
- Potentially higher risk of infection
- Not ideal for overnight wear
Silicone Hydrogel as a SCL Material
- Allow 5x more oxygen through
- Oxygen permeability is dependent on silicone rather than on water content
- Initial SiHy lenses were treated with coating due to poor wettability but no longer required
Advantages of Silicon Hydrogel Lenses
- High oxygen permeability
- Easier to handle
- More durable
- Extended wear options available
Disadvantages of Silicon Hydrogel Lenses
- Slightly higher price
- Higher risk of GPC, but this is reduced in newer reduced modulus lenses
Disposable Lenses in Alloa Specsavers
Easyvision Linarial
- Spherical
- Toric
- Multifocal
Dailies Total 1
- Spherical
Linarial Spherical SCL Characteristics
- Coopervision My Day
- BC/TD: 8.4/14.2
- SiHy (Stenfilcon A)
- Dk/t:100 (at -3.00DS)
- H20 Content:54%
- UV: Yes
- Rx Range:
- -6.00DS to +5.00DS in 0.25D steps
- Upto -12.00DS
- Upto +8.00DS
Monthly Lenses in Alloa Specsavers
Opteyes
- (XR) Spherical
- (XR) Toric
- Multifocal
- Toric Multifocal
Uvicia Monthly
- Spherical
- Toric
Opteyes Spherical SCL Characteristics
- Coopervision Biofinity
- BC/TD: 8.6/14.0
- SiHy (Comfilcon A)
- Dk/t: 171
- H20 Content:48%
- UV: No
- Rx Range (XR Range):
- Upto ±20.00DS
- Upto -5.75DC
Preservatives in SCL Solutions
- Example is polyhexanide
- Can cause toxicity or hypersensitivity
- Can manifest as hyperaemia, punctate keratopathy or corneal infiltrates
- cause bother for individuals with allergies
What to do if Problems With Preservatives in Solution
- Reduce wear time if minor reaction
- Switch to daily lenses
- Hydrogen Peroxide solutions
Specsavers Easyvision Allpurpose Solution Features
- Cleaning, disinfecting, hydrating and replenishing all in one
- Minimum of 4 hours to clean the lens
- Once opened discarded after 3 months
Specsavers Easyvision Allpurpose Solution Ingredients
Sodium Chloride- Tonicity Adjuster
Boric Acid - Disinfectant
Sodium Tetraborate - Buffer
Sodium Citrate - Buffer
Poloxamer 407 - Cleaner
Hyaluronic Acid - Lubricant
Disodium Edetate 0.02% - Preservative/chelating agent
Polyhexamethylene 0.0001% - Preservative
Solution Ingredient Purposes
Preservative
- Maintains sterility of solution
Viscosity Enhancer
- Thickens solution
Tonicity Adjuster
- Maintains ideal salt concentration
Buffer
- Maintain pH between 7.0 and 7.4
Disinfectant
- To disinfect
Chelatin Agent
- Prevent protein bonding to lens
Hydrogen Peroxide Solutions
- Gold standard of SCL care
- Higher disinfecting power and are able to disinfect inside the polymer matrix of the lens
- Do not feature a preservative so are excellent option for atopic patients
- Is toxic to ocular surface if not neutralised
- 6 hours to neutralise solution from 3% to 0.1%
Hydrogen Peroxide Solution Steps
- Remove lenses and place into R&L baskets
- Rinse each lens for circa 5s in their baskets with hydrogen peroxide 3%
- Fit case to line with hydrogen peroxide 3%
- Place lenses into case and solution will start to bubble. Store upright
- Allow to soak for atleast 6 hours (overnight preferred)
- Rinse with sterile saline prior to insertion
- Discard old solution from case, rinse with fresh hydrogen peroxide and leave to air dry.
Hydrogen Peroxide Solution Ingredients
3% Hydrogen Peroxide - Active ingredient
Sodium Chloride - Tonicity Adjuster
Sodium Phosphate - Buffer
Poloxamer - Polymer surfactant
HEDP - Prolongues lifespan
Purified water - Solvent
Importance of Tonicity Adjuster
- Too high salt concentration and cornea will dry out
- Too low salt concentration and cornea will swell up
