ABO NOCE Basic Opticianry Optical Instrumentation Use Questions and Answers

Question 1

An optician uses a lens clock to measure the surface curves of a lens.
The instrument provides a direct reading of the surface power in diopters, but it is calibrated for a specific refractive index.
If a lens clock calibrated for crown glass (n=1.53) is used to measure the front surface of a polycarbonate lens (n=1.586), and the reading is +6.00 D, what is the actual surface power?

Accepted Answer

Slightly higher than +6.00 D

Answer

Slightly lower than +6.00 D

Answer

Exactly +6.00 D

Answer

It cannot be determined without the radius of curvature

Question 2

While verifying a pair of finished eyewear with a manual lensometer, the optician cannot center the target mires within the reticle for the right lens, even with the lens platform centered. The target is displaced 2 rings upward and 1 ring toward the nasal side. How should the induced prism be recorded?

Accepted Answer

2Δ Base Up, 1Δ Base In

Answer

2Δ Base In, 1Δ Base Up

Answer

2Δ Base Down, 1Δ Base Out

Answer

2Δ Base Up, 1Δ Base Out

Question 3

A patient presents with a high-power prescription (-11.50 D) that was refracted at a vertex distance of 12mm. The chosen frame will sit at a vertex distance of 15mm. Which instrument is essential for the optician to use to ensure the compensated lens power is calculated correctly?

Accepted Answer

Distometer

Answer

Pupilometer

Answer

Lens Clock

Answer

Polariscope

Question 4

An optician is using a polariscope to inspect a new pair of plastic lenses that have been edged and mounted into a metal frame. They observe bright, spiky patterns of light flaring from the edges of the lens. What is the most likely cause of this observation?

Accepted Answer

The lenses are oversized and under stress from the frame.

Answer

The lens is made of polycarbonate material.

Answer

The lenses have a high-quality anti-reflective coating.

Answer

The lenses are undersized for the frame.

Question 5

When using a pupilometer to take a monocular pupillary distance (PD) measurement for progressive lenses, what is the correct procedure?

Accepted Answer

Have the patient look at the illuminated internal target and align the hairlines with the corneal reflections of each eye independently.

Answer

Ask the patient to look at the optician's open right eye, then open left eye, while the optician measures with a ruler.

Answer

Align the vertical hairline on the right pupil, then the left, and add the two numbers together for the total PD.

Answer

Measure the distance from the outer canthus of one eye to the inner canthus of the other eye.

Question 6

Which of the following instruments directly measures the sagittal depth of a lens curve to determine its surface power?

Accepted Answer

Lens Clock

Answer

Lensometer

Answer

Pupilometer

Answer

Distometer