toric fitting and aftercare Flashcards
PX:
RE 7.75 along 90 and 8.00 along 180
LE 7.80 along 90 and 7.80 along 180
What is the astigmatism in both eyes and is it WTR or ATR?
RE = WTR astigmatism of 1.25D
LE = no ast
If there is lenticular astigmatism, which is the best lens option?
toric SCL or front surface RCL
what is a disadvantage of a front surface RCL?
poor stability
what are the 3 different toric lens designs or RCLs?
front surface toric
back toric
bi-toric
what are the 2 diff scl toric designs?
prism ballast
dynamic stabilisation
what are the diff types of prism ballast?
traditional
peri-ballast
reverse prism
what are the 2 diff types of dynamic stabilisation?
dual thin zone
acceleration stabilisation
what are the 2 most important things in H&S in toric aftercare?
- address stability of vision with your patients
- how does it compare to specs
which type of RCL is useful in residual astigmatism?
front surface toric
what is the most important part of assessment of toric fit?
stability of lens
what are some signs of unstable rotation?
vision fluctuation and increased lens awareness
What does LARS stand for?
L- left
A - add
R - right
S - subtract
what is different about a toric over refraction
normal o/r, when changing power of cyl, adjust in steps available for the fitted lens
check vision with specs to compare acuities
why is the keratometry/prescription relationship less important in soft toric lenses?
these drape over the cornea
how does dual thin zone work?
double slab off
thinner areas fit under the lids
what manufacturer uses dual thin zone stabilisation technique?
Alcon dailies toric
how does accelerated stabilisation work?
4 active zones with a thicker profile in the mid-periphery wihch minimise lens rotation
thinnest portion rest under lids
which manufacturer uses accelerated stabilisation?
J&J
how long do you need to wait for the lens to be stable?
5 mins (byki)
if the lens is stable after 5 mins what do you do?
order with any axis compensation if neede
if the lens is unstable after 5 mins what do you do?
fit diff type of lens - unlikely to improve with time
if there is a rotation of aroud 5 degrees - what could this indicate and what would you do to fix it?
LOOSE LENS - use a steeper BOZR
(clinical pearl from byki)