TORIC SOFT CL

Question 1

TORIC CL CONSIDERATIONS

Answer 1

● Different powers in two mutually perpendicular meridians
● Different methods and designs for stabilization

Question 2

TORIC DESIGN CONSIDERATIONS

Answer 2

● Surface design (manufacture)
● Stabilization
● Reference marks (type and position)
● Lens thickness variation
● Water content

Question 3

TORIC SOFT CL MANUFACTURING TECHNIQUES

Answer 3

● Crimping and lathing (Toric machining)
● Molding (or molding and lathing)
● Spin-casting (or spin-casting and lathing)

Question 4

TORIC SURFACE DESIGN

Answer 4

FRONT SURFACE TORIC
BACK SURFACE TORIC
BITORIC (UNCOMMON)

Question 5

TORIC CL STABILIZATION METHODS

Answer 5

● Prism ballast
● Truncation
● Peri-ballast
● Double slab-off
● Reverse prism

Question 6

T/F
IN TORIC CLS Good vision needs stable spherical axis location

Answer 6

F

Good vision needs stable cylinder axis location

Question 7

TORIC LENS DESIGN AIMS

Answer 7

● Maximize predictability of axis location
● Make axis location independent of Rx
● Maximise physiological performance

Question 8

TORIC STABILIZATION

PRISM BALLAST

Answer 8

● 1 to 1.5 AD base down
● Stabilized by prism-induced thickness
differences
● Reduced oxygen transmissibility
● Discomfort with lens-lid interaction

Question 9

TORIC STABILIZATION

TRUNCATION

Answer 9

● Alignment of truncation with lower lid margin is a stabilizing factor
● Truncation is a source of discomfort
● Truncation not always successful
● More patient visits required

Question 10

TORIC STABILIZATION

PERI-BALLAST

Answer 10

● Minus carrier converted into a prism base down effect
● Uses thickness differences as the stabilizing component
● Discomfort with lens-lid interaction at the thicker inferior half
● Reduced oxygen transmissibility in thicker regions
● Thinner superiorly, thicker inferiorly
● Orientation principle similar to prism ballast
● Similar overall thickness to spherical lens
● Prism-free optic

Question 11

TORIC STABILIZATION

DOUBLE SLAB OFFF

Answer 11

● Better comfort because of reduced lens thickness
● Thin zone superiorly and inferiorly
● Lid forces maintain orientation
● Overall thinner lens
● Lens is symmetrica

Question 12

USED TO ASSESS LENS ORIENTATION IN SITU

Answer 12

REFERENCE MARKS

Question 13

IMPLICATION OF TORIC SCL THICKNESS VARIATION

Answer 13

● Fitting
● Oxygen transmissibility
● Mechanical and physiological corneal chang

Question 14

LENS ORIENTATION IS ___________ DEPENDENT

Answer 14

thickness-difference

Question 15

thickness-difference ARE THE RESULT OF

Answer 15

LENS DESIGN AND RX FACTORS

Question 16

Increased thickness differential indicates a decline in oxygen__________________ from one lens region to the next

Answer 16

transmissibility

Question 17

WTR lenses have lower average thickness than ATR in________________ designs

Answer 17

prism ballast

Question 18

Prism ballast designs have greater:

Answer 18

○ thickness variation
○ lens mass
○ localized pressure on cornea @ prism base

Question 19

PRISM BALLAST’S THICKNESS VARIATION RESULTS IN

Answer 19

• increased central, temporal and inferior corneal thickness
• greatest corneal compromise @ inferior limbus