ABO NOCE Basic Opticianry Prescription Transposition 5

Question 1

Which of the following prescriptions is the minus cylinder equivalent of +1.50 +1.00 x 180?

Accepted Answer

+2.50 -1.00 x 090

Answer

New sphere = +1.50 + 1.00 = +2.50; new cyl = -1.00; new axis = 180 - 90 = 090.

Question 2

What is the purpose of transposing a prescription?

Accepted Answer

To convert between plus and minus cylinder notation

Answer

Transposition converts a prescription between plus and minus cylinder forms while keeping the optical effect identical.

Question 3

If a prescription is -1.75 -0.50 x 020, what is the spherical equivalent?

Accepted Answer

-2.00

Answer

SE = -1.75 + (-0.50 ÷ 2) = -1.75 + (-0.25) = -2.00.

Question 4

Transpose -0.25 -0.75 x 135 into plus cylinder form.

Accepted Answer

-1.00 +0.75 x 045

Answer

New sphere = -0.25 + (-0.75) = -1.00; new cyl = +0.75; new axis = 135 - 90 = 045.

Question 5

In a spherocylindrical lens, the two principal meridians are always separated by:

Accepted Answer

90°

Answer

The two principal meridians of any toric (spherocylindrical) lens are always 90° apart.

ABO NOCE Basic Opticianry Practice Test