Prescription AnalysisQuestion 33 of 100
In the Rx -2.50 -0.75 x 180, what does the 180 represent?
a.The sphere power
b.The axis of the cylinder
c.The add power
d.The prism base
Explanation
The number after the 'x' is the cylinder axis, expressed 1 to 180 degrees, indicating the orientation of the cylinder correction. Here the axis is 180 degrees.
Practice all 100 questions free — no signup required.
Related questions on this topic
- Transpose the Rx: +2.00 -1.00 x 090 into plus-cylinder form.
- Transpose the Rx: -3.00 +2.00 x 045 into minus-cylinder form.
- A patient has Rx OD -1.00 DS. What does 'DS' indicate?
- Per ANSI Z80.1 tolerances, verifying a finished single-vision lens checks that the measured power falls within what?
- A lens is decentered 4 mm from the optical center for a +5.00 D lens. How much prism results (Prentice's rule)?
- When reading an Rx, which value is always a plus number on a bifocal?
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against ABO (American Board of Opticianry) Certified Optician Exam · How we review