8.2 Transposition

Question 1

What is transposition

Answer 1

Flipping from plus cyl to minus cyl (or vice versa)

Question 2

Why is transposition important

Answer 2

Ophthalmologists work in plus cyl due to it matching the cyl of corneal topography. Optometry works in minus cyl due to spectacle lenses power from the back surface of the lens is in minus cyl

Question 3

With the rule in plus cyl vs minus cyl

Answer 3

WTR in plus cyl 090 vs WTR in minus cyl 180

Question 4

Against the rule in plus cyl vs minus cyl

Answer 4

ATR in plus cyl is 180 vs ATR in minus cyl is 090

Question 5

WTR plus cyl

Answer 5

90

Question 6

ATR plus cyl

Answer 6

180

Question 7

WTR minus cyl

Answer 7

180

Question 8

ATR minus cyl

Answer 8

90

Question 9

Step 1 of transposition

Answer 9

Take the last column and flip axis 90deg by adding or subtracting 90 ( needs to land between 0 and 180)

Question 10

Step 2 to transposition

Answer 10

Take the middle column and switch the sign but keep the number the same

Question 11

Step 3 to transposition

Answer 11

Trickiest step. Add the original sign and number of column two to the first column sign and number (number line!)

Question 12

Steps to tranposition

Answer 12

Start far right and work backward. Axis goes 90deg away. Then flip sign of cyl but keep number. Then add the original cyl with sign to the sph column with sign