CL (Soft CL) Flashcards
Parameters (BBL-CLW) (WRF-TIM)
- Base curve
- Back vertex power
- Lens diameter, optic zone diameter
- Center thickness, edge thickness
- Lenticulation / Edge design
- Water content
- FDA groupings
- Wear schedule approval
- Replacement modality
- Tints
- Inversion markers
- Manufacturing technique
also referred to as Sagittal depth (sag) or Vault
Base Curve
tend to be much flatter than K due to large diameter
Base curve
Base curve typical range
8.00 to 9.20mm
determined by BC, front curve, CT, n
Power
assume that LL is plano for most SCLs
Power
Power: effective power not altered by lacrimal lens (True or False)
True
larger than RGPs in general
Lens diameter/ optic zone
increases stability & comfort
Lens diameter/optic zone
Lens diameter/optic zone typical mm
13.5 to 15mm
creates greater sag, resulting in need for flatter BC’s
Lens diameter/optic zone
decreases tear exchange
Lens diameter/optic zone
thinner than RGPs due to decreased fragility of material (greater flexibility)
Center & Edge Thickness
affects Dk/L
Center Edge & Thickness
Center & Edge Thickness: edge profile may be more important to consider (True/False)
True
Min CT = ______, increases for higher water content materials
0.03mm
- due to large diameter, all SCLs are lenticulated to maintain thin profile
- edge designs vary
Lenticulation/Edge design
water is bound within a hydrophilic polymer matrix to provide flexibility & oxygen permeability
Water content
The amount of _____ determines material characteristics
Water
Water content range
Range: 25% to 74%
Low: <50%
High: >50% (FDA)
Water content (Low) (GLUCEF)
- Good durability & handling
- Fewer deposits
- Lower Dk
- Can be made thinner
- Used more often than daily wear
- Exception: SiHy
Range: Low: <50%
Water content (High) (HUMMP)
- Higher Dk
- Used more often than extended wear
- More deposits
- Poorer durability & handling
- Must be made thicker
Water content: For ___________, less water content means higher silicone content, and therefore higher Dk
Silicone hydrogels
Water content
PureVision:
Focus N&D:
PureVision: 36% water Dk: 110
Focus N&D: 24% water, Dk: 140
Silicone hydrogels: hydrophobic
Silicone
Silicone hydrogels: hydophilic
Hydrogel
What is other name for silicone
Polydimethylsiloxane
Silicone Hydrogels AerGel Technology (WOSH)
-Oxygen
-Water
-Hydrogel matrix
-Silicone matrix
FDA Groupings
Group 1: low water, non-ionic
Group 2: high water, non-ionic
Group 3: low water, ionic
Group 4: high water, ionic
In FDA groupings, what groups are non-ionic
Group 1 & 2
In FDA Groupings, what groups are ionic
Group 3 & 4
In FDA Groupings, what groups are low water
Group 1 & 3
In FDA Groupings, what groups are high water
Group 2 & 4
Water Schedules: wear during waking hours only, no overnight wear
Daily wear
Water Schedules: wear overnight up to 7 days in a row, any lens approved for EW
Extended Wear
Water Schedules: wear continuously up to 30 days in a row, only for silicone hydrogels
Continuous wear
Replacement Modality (CFD)
- Conventional
- Frequent replacement
- Disposable
lens is replaced when it needs replacing
Conventional
if a lens is lost/damaged, a replacement must be purchased
Conventional
Conventional SCL typically lasts
12 months for a SCL
patient receives one pair of lenses at a time
Conventional
more lens care required, more deposit related complications
Conventional
also called Programmed Replacement
Frequent Replacement
Frequent Replacement: lens is replaced on a regular schedule ___weeks to ____months
2 weeks to 3 months