Prescription Transposition Flashcards
7 cards from real ABO NOCE Basic Opticianry practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Prescription Transposition flashcards as text
Transpose -3.00 +1.50 x 090 into minus cylinder form.
Answer: -1.50 -1.50 x 180
New sphere = -3.00 + 1.50 = -1.50; new cylinder = -1.50; new axis = 090 + 90 = 180.
What is the spherical equivalent of +2.00 -1.00 x 045?
Answer: +1.50
Spherical equivalent = sphere + half the cylinder power = +2.00 + (-0.50) = +1.50.
After transposing +1.00 -2.00 x 030, what is the new sphere?
Answer: -1.00
New sphere = original sphere + original cylinder = +1.00 + (-2.00) = -1.00.
A prescription reads plano -2.50 x 160. What is its plus cylinder transposition?
Answer: -2.50 +2.50 x 070
New sphere = 0.00 + (-2.50) = -2.50; new cyl = +2.50; new axis = 160 - 90 = 070.
Which step is performed LAST when transposing a prescription?
Answer: Rotate the axis 90°
The final step of transposition is rotating the axis by 90° (add or subtract 90, keeping result between 1 and 180).
Transpose -0.50 +2.00 x 110. What is the new axis?
Answer: 020
110 + 90 = 200, which exceeds 180, so subtract 180: 200 - 180 = 020.
The power cross for -1.00 DS shows which values in both meridians?
Answer: -1.00 in both meridians
A spherical lens (DS) has the same power in every meridian, so both principal meridians on the power cross read -1.00.