Practice Quiz

ABO NOCE Basic Opticianry

Category - Instrumentation

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What does a PD ruler not measure?
  1. Vertex distance
  2. The B measurement of a frame
  3. The pupillary distance of a patient
  4. The ED measurement of a frame
Explanation
Answer: A - A PD ruler does not measure vertex distance.

A distometer is used to measure vertex distance. The PD ruler can be used to measure the ED, B and A sizes of the frame and lens. It can also be used to measure the pupillary distance of a patient.

On a frame, the PD ruler can be used to measure the bridge and eye size of the frame along with the temple length.
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