FITTING TORIC SOFT CL

Question 1

TORIC SCL INDICATIONS

Answer 1

● Visual compromise from residual astigmatism
● Unsatisfactory VA with best sphere
● High sphere to cylinder ratio
● RGPs not tolerated

Question 2

REASONS FOR USING TORIC SCLs

Answer 2

● Refractive astigmatism
● Spherical SCLs failed to mask corneal
astigmatism
● RGP lenses induced residual astigmatism
● RGP lenses caused discomforT

Question 3

SUMMARY CRITERIA FOR USE

Answer 3

● Degree of astigmatism
● Ocular dominance
● Viability of the alternatives
● Assessment of patient’s visual need

Question 4

TORIC SCL ASSESSMENT TO FIT

Answer 4

GOOD FIT
TIGHT FIT
LOOSE FIT

Question 5

WHAT FIT?
Full corneal coverage, good centration and movement, quick return to axis if mislocated

Answer 5

GOOD FIT

Question 6

WHAT FIT?

good centration, initially comfortable, little or no movement. Slow return to axis if mislocated

Answer 6

TIGHT FIT

Question 7

WHAT FIT?
excessive movement, poor centration,
uncomfortable. Lens orientation
unstable and inconsistent

Answer 7

LOOSE FIT

Question 8

TORIC SCL FITTING METHODS

Answer 8

SPECIAL SPHERICAL TRIAL LENS
TORIC SCL TRIAL LENS
EMPIRICAL PRESCRIBING

Question 9

quick return to axis if mislocated

WHAT FIT

Answer 9

GOOD FIT

Question 10

slow return to axis if mislocated

WHAT FIT

Answer 10

TIGHT FIT

Question 11

lens orientation unstable and inconsistent

WHAT FIT

Answer 11

LOOSE FIT

Question 12

Reference mark on lens at ___ and __ o’clock or ____ o’clock

Answer 12

3, 9, 6

Question 13

HOW TO MEASURE LENS ROTATION

Answer 13

○ narrow slit-lamp beam
○ spectacle cylinder in trial frame
○ protractor scale eyepiece graticule

Question 14

Average lens rotation is________ degree nasal,

Answer 14

5-10

Question 15

LARS

Answer 15

LEFT ADD
RIGHT SUBTRACT

Question 16

CATS

Answer 16

CLOCKWISE - ADD
ANTICLOCKWISE - SUBTRACT

Question 17

Interactions with lids moves _______ meridian
towards ___________

Answer 17

THINNES, VERTICAL

Question 18

WHAT IS THE DOMINANT STABILIZING COMPONENT

Answer 18

UPPER LID

Question 19

T/F

WITH RESPECT TO ROTATIONAL INFLUENCE

OBLIQUE > WTR > ATR

Answer 19

T

Question 20

TORIC SCL FITING

Answer 20

1. Measure refractive error & vertex distance
2. Select toric lens design
3. Select trial lens power to match corneal-plane refraction
4. Select BOZR and/or TD
5. Measure meridional orientation (axis mislocation)
6. Compute final prescription including axis compensation

Question 21

TORIC SCL PHYSIOLOGICAL CONSIDERATIONS

Answer 21

1. Complications such as cornea oedema and corneal vascularization more likely due to the increased lens thickness
2. If problems occur, use a high water content material (55% or greater)
3. If problems persist, refit with RGP lense

Question 22

TORIC SCL DIFFICULT CASES

Answer 22

LOW SPHERICAL COMPONENTS
OBLIQUE CYLINDERS
HIGH CYLINDERS

Question 23

TORIC SCL PROBLEM SOLVING

Answer 23

Check accuracy of baseline data e.g ocular refraction, K readings

Perform sphero-cylindrical over- refraction (SCO)

Question 24

ROUTINE FOR TORIC SCL ASSESSMENT

Answer 24

1. Case history (vision)
2. Measure visual acuity (VA)
3. Spherical over-refraction and VA
4. Sphero-cylindrical over-refraction and VA
5. Check meridonal orientation of lens (slit-lamp)
6. Check stability of fit
7. Get patient to move eyes and recheck meridonal orientation
8. For mislocating lens, rotate to intended position and check if vision improves
9. Use table of calculated angles of mislocation based on sphero-cylindrical over-refraction
10. Measure power and axis of toric SCL
11. Check ocular refraction and keratometry for comparison with baseline