ABO NOCE Basic Opticianry Optical Instrumentation Use 3

Question 1

When measuring the seg height of a bifocal lens in the frame, which instrument is most appropriate?

Accepted Answer

A seg height ruler or millimeter rule referenced from the lower frame rim

Answer

Seg height is measured in millimeters from the bottom of the lens or lower frame rim to the top of the segment, using a millimeter ruler.

Question 2

In a lensometer, what do the three lines in one meridian and a single line in the other meridian represent?

Accepted Answer

Two power meridians of a toric (cylindrical) lens

Answer

The two sets of lines (three lines and one line) represent the two principal meridians of a toric lens, used to read sphere and cylinder power.

Question 3

When using a focimeter (lensometer) to verify a lens power of -3.00 -1.25 × 090, which set of lines do you focus first?

Accepted Answer

The lines running at 180° (the sphere meridian)

Answer

By convention, you first focus the lines running parallel to the cylinder axis to find the sphere power, then rotate to find the cylinder power.

Question 4

A hand neutralization technique uses trial lenses to cancel lens power. If a +2.00 D trial lens fully neutralizes movement, the unknown lens power is:

Accepted Answer

-2.00 D

Answer

A +2.00 D trial lens neutralizes a -2.00 D lens because equal and opposite powers cancel, resulting in no apparent movement.

Question 5

Which of the following best describes the purpose of the axis wheel on a lensometer?

Accepted Answer

It rotates the target to align with the cylinder axis

Answer

The axis wheel rotates the internal target so the lines can be aligned with the cylinder axis meridian of the lens being measured.

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Optical Instrumentation Use 3