CPO Lensometry and Spectacle Lens Verification 2

Question 1

To determine the add power of a flat-top bifocal lens, a technician should:

Accepted Answer

Subtract the distance power reading from the near segment power reading

Answer

Read the add directly from the segment without measuring the distance zone

Answer

Add the sphere and cylinder powers together

Answer

Measure the upper half of the lens only

Question 2

Prismatic power in a spectacle lens is measured in which unit?

Accepted Answer

Prism diopters (Δ)

Answer

Diopters (D)

Answer

Millimeters of displacement

Answer

Degrees of angular deviation

Question 3

When the lensometer target mire appears displaced from the center of the reticle, this indicates:

Accepted Answer

Prismatic power is present in the lens

Answer

The cylinder axis is misaligned

Answer

The add power is incorrect

Answer

The sphere power is out of range

Question 4

For a progressive addition lens (PAL), where should the lensometer be positioned to measure the distance power?

Accepted Answer

Through the distance zone in the upper portion of the lens

Answer

Through the near zone at the bottom of the lens

Answer

Through the intermediate corridor

Answer

Through the widest part of the lens

Question 5

A lens prescription reads -1.00 -0.50 x 180. When transposed to plus cylinder form, it becomes:

Accepted Answer

-1.50 +0.50 x 090

Answer

-0.50 +0.50 x 090

Answer

-1.50 +0.50 x 180

Answer

-0.50 -0.50 x 090

Question 6

The base direction of prism in a spectacle lens refers to the direction:

Accepted Answer

The base (thickest edge) of the prism points

Answer

The apex (thinnest edge) of the prism points

Answer

Light is deviated by the prism

Answer

The patient's eye turns in response to the prism

Question 7

When measuring a high-powered lens (e.g., +14.00 D aphakic correction) on a standard lensometer, the technician may find that:

Accepted Answer

The power exceeds the lensometer's measurement range

Answer

The lens absorbs too much light to allow measurement

Answer

The mire appears brighter than normal

Answer

The ink dots will not adhere to the lens surface