ABO NOCE Basic Opticianry Prescription Transposition 2

Question 1

Transpose -3.00 +1.50 x 090 into minus cylinder form.

Accepted Answer

-1.50 -1.50 x 180

Answer

New sphere = -3.00 + 1.50 = -1.50; new cylinder = -1.50; new axis = 090 + 90 = 180.

Question 2

What is the spherical equivalent of +2.00 -1.00 x 045?

Accepted Answer

+1.50

Answer

Spherical equivalent = sphere + half the cylinder power = +2.00 + (-0.50) = +1.50.

Question 3

After transposing +1.00 -2.00 x 030, what is the new sphere?

Accepted Answer

-1.00

Answer

New sphere = original sphere + original cylinder = +1.00 + (-2.00) = -1.00.

Question 4

A prescription reads plano -2.50 x 160. What is its plus cylinder transposition?

Accepted Answer

-2.50 +2.50 x 070

Answer

New sphere = 0.00 + (-2.50) = -2.50; new cyl = +2.50; new axis = 160 - 90 = 070.

Question 5

Which step is performed LAST when transposing a prescription?

Accepted Answer

Rotate the axis 90°

Answer

The final step of transposition is rotating the axis by 90° (add or subtract 90, keeping result between 1 and 180).

ABO NOCE Basic Opticianry Practice Test