ABO NOCE Basic Opticianry Optical Instrumentation Use 4

Question 1

On a lensometer, what does the drum reading indicate when the target lines are sharpest and the axis is at 45°?

Accepted Answer

The cylinder power at axis 45°

Answer

When lines are sharpest with the axis wheel at 45°, the cylinder axis of the lens is 45°, and the drum reading gives the cylinder power.

Question 2

A Geneva lens clock placed on a flat (plano) surface should read:

Accepted Answer

0.00 D

Answer

A properly calibrated Geneva lens clock reads 0.00 D on a flat surface, confirming the instrument is zeroed correctly.

Question 3

When using a pupillometer for a patient with a significant facial asymmetry, which measurement mode provides the most accurate optical center placement?

Accepted Answer

Monocular PD measurement from the center of the nose

Answer

Monocular PD measurement references each eye independently from the nasal bridge, providing the most accurate placement for asymmetrical faces.

Question 4

What is the function of the ink marker on a lensometer?

Accepted Answer

To mark the optical center and axis on the lens surface

Answer

The ink marker dots the lens surface through the lensometer stage, indicating the optical center and reference axis on the lens.

Question 5

To verify the add power of a bifocal lens, a technician reads the distance power first, then repositions the lens to read the near segment. The add power equals:

Accepted Answer

Near power minus distance power

Answer

Add power = near (segment) power − distance power; this difference represents the additional plus power of the reading segment.

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Optical Instrumentation Use 4