Soft Toric Lenses

Question 1

What should you assume vertex distance is (unless otherwise specified)

Answer 1

12 mm (0.012)

Question 2

What power should you compensate the Rx?

Answer 2

Over plus or minus 4.00 Diopters

Question 3

Compensation Formula

Answer 3

FC= F
——
1 - (dF)

F is the power and d is vertex distance in mm

Question 4

Compensate a -5.00 Rx

Answer 4

-5.00
——
1- (0.012)(-5.00)
= -4.7169
* round to nearest quarter of a Diopter
-4.75 D

Question 5

What is the max cyl that you can use a sph equivalent?

Answer 5

1.00 Diopter

Question 6

What is the sph equivalent for :

-2.50 -0.50 x 180

Answer 6

-2.75

Add half of the cyl to the sph and drop the rest

Question 7

What is the sph equivalent for -2.50 -0.25 x 180

Answer 7

-2.50

Can’t split 0.25 so just ignore it

Question 8

Should you compensate or sph equivalent first?

Answer 8

Always compensate (in both meridians) then do sph equivalent

Question 9

Compensate
OD -10.50-0.50x165
OS -9.25-0.75x010
Vertex distance is 12 mm

Answer 9

OD 
            FC165.                                           
-10.50
———
1-(0.012)(-10.50)
= -9.32 D
= -9.25 D

FC075
-11.00
———
1-(0.012)(-11.00)
= -9.71
= -9.75 D

OD = -9.25-0.50 x 165
Sph E = -9.50 D

OS 
Fc010 
-9.25
———
1-(0.012)(-9.25)
=-8.33
= -8.25

Fc100
-10.00
———-
1-(0.012)(-10.00)
=-8.93
= -9.00

OS= -8.25-0.75 x 010
Sph E= -8.62
-8.50

Question 10

Compensate -6.00+2.00x130

Answer 10

First transpose: -4.00-2.00x040
Fc 040
-4.00
——-
1-(0.012)(-4.00)
= -3.82
= -3.75

Fc140
-6.00
——-
1-(0.012)(-6.00)
= -5.60
= -5.50

-3.75-1.75x140
(Can’t sph equivalent..must order toric lens)

Question 11

What is the LARS rule?

Answer 11

If a toric lens rotates to the left you ADD to the axis

If a toric lens rotates to the right you SUBTRACT from the axis

Question 12

What axis can you get in toric lenses?

Answer 12

Toric lenses are available in to degree increments

Question 13

What cyl power can you get for soft toric lenses?

Answer 13

Start at -0.75 and increase in 0.50 steps

Question 14

Your pt is wearing -2.50-1.25x090 lenses.

Under slit lamp exam you notice the lens is rotated 20 degrees to the right. What lens do you change to?

Answer 14

-2.50-1.25x070

Right add minus

Question 15

The patient’s k readings are
41.00/42.00 @180
What is a better bc
8.2, 8.6 or8.8?

Answer 15

The K readings are flat so the best bc would be 8.8

Question 16

Compensate

-3.00-2.00 x 070

Answer 16

FC 070
-3.00 (not over 4 so don’t compensate at 070)

FC160
-5.00
——
1-(0.012)(-5.00)
= -4.72
= -4.75

Rx is -3.00-1.75x070

Question 17

Patient is wearing -2.25-1.25x040 lens
Lens is rotated 10 degrees to the left.
What do you do?

Answer 17

Change lens to

• 2.25-1.25x050
• LEFT ADD

Question 18

Compensate
-5.00+2.75x170
Vertex Distance is 13 mm

Answer 18

First Transpose
-2.25-2.75x080

FC 080
-2.25

FC170
-5.00
——
1-(0.013)(-5.00
= -4.69
= -4.75

Comp rx:

• 2.25-2.50x080
• Can’t order toric lenses with 2.50 cyl so
• 2.25-2.25x080

Question 19

Patient is wearing
-2.25-2.25x080
Lens is rotated 15 degrees to the right
What do you do?

Answer 19

Change to
-2.25-2.25x070
(Only works in increments of 10 degrees not 15..so you can try 70 or 60)

Question 20

If a 8.8 BC is too loose, what BC would you re order?

Answer 20

8.6 or 8.7

Question 21

Benefit of silicone hydrogel lenses

Answer 21

Allow more oxygen transmission

Question 22

If k reading is WTF but RX is ATR can you fit an RGP?

Answer 22

No, soft toric