SCL Astig

Question 1

4 things to assess when figuring out if you should fit a toric SCL:

Answer 1

1) topo (pingueculas = difficult)
2) lid characteristics
3) Rf error
4) tolerance to cyl axis rotation

Question 2

3 most influential characteristics on toric SCL stability: [PDL]

Answer 2

1) palpebral aperture size - smaller = more stable
2) degree of myopia - more myopia = less stable
3) lid angles

Question 3

lid angles - (positive/negative) more common. Which edge is higher? Which direction does it usually rotate in?

Answer 3

positive: temporal: temporal

Question 4

HIGHER minus powers are less stable with p____ b____ designs, while LOWER minus powers are less stable with double ___-___ designs

Answer 4

prism-ballasted

double slab-off

Question 5

how to determine a pt’s tolerance to axis rotation: ____ twist test

Answer 5

becherer

1) perform SCOR
2) rotate cyl until pt DEFINITELY notices blur
- ——-rotation 5-10 degree tolerance you may want to consider hybrid/GP

Question 6

where’s the thicker edge of an SCL in a WTR cornea? ATR cornea? Oblique?

Answer 6

WTR: top/bottom
ATR: side/side
Oblique: along more MINUS meridian
-location of toricity - usually back surface, but doesn’t matter d/t flexure/draping of lens

Question 7

T/F: lens markings indicate the direction of the axis

Answer 7

FALSE - they’re just markers for the doc to see rotation of the lens to a consistent place

Question 8

what’s the primary concern for fitting soft torics?

-30 degrees off can lead to ___ diopter of induced lens cyl

Answer 8

refractive cyl - NOT corneal - IMPORTANT!!! toricity

1D

Question 9

assessing rotation: lens should not rotate more than __-__ degrees - if it does, use a different BC or lens design

Answer 9

15-20; or 5-10 deg during blink

Question 10

Toricity usually located in which part of the SCL?

-The AMOUNT of toricity equals the patient’s ______ subjective refraction

Answer 10

optic zone;

-VERTEXED - don’t forget!!