CPO FREE CPO Ophthalmic Instrument Maintenance and Calibration Questions and Answers 2

Question 1

When replacing a slit lamp bulb, oil from fingerprints is left on the new bulb. What is the most likely immediate consequence during the next use?

Accepted Answer

Creation of hot spots that reduce the bulb's lifespan.

Answer

A distorted or uneven slit beam.

Answer

A significant color temperature shift in the illumination.

Answer

The bulb will fail to illuminate due to a short circuit.

Question 2

A manual phoropter's Jackson Cross Cylinder (JCC) axis knob feels unusually stiff and occasionally slips during rotation. What is the most probable cause that requires professional service?

Accepted Answer

Debris has accumulated around the internal thrust washer mechanism.

Answer

The axis indicator arrow is simply misaligned.

Answer

The patient's forehead is pressed too firmly against the rest.

Answer

The auxiliary lens dial is not set to the open position ('O').

Question 3

During a Goldmann applanation tonometer calibration check, the feeler arm floats perfectly at the '0' and '2' (20 mmHg) positions but falls toward the examiner at the '6' (60 mmHg) position, even when the dial is at 6.05. This indicates:

Accepted Answer

The tonometer is underestimating high intraocular pressures.

Answer

The tonometer is reading accurately across all pressures.

Answer

The tonometer is overestimating high intraocular pressures.

Answer

The calibration bar is being used incorrectly.

Question 4

An automated lensmeter consistently fails to read high-plus, slab-off bifocal lenses accurately, often giving an 'error' message. Which of the following is the most likely reason for this specific failure?

Accepted Answer

The complex prism and rapid power changes of the slab-off line interfere with the sensor array.

Answer

The lens stop is dirty or misaligned.

Answer

The instrument needs to be recalibrated with a standard single-vision lens.

Answer

The lens has a highly reflective or mirror coating.

Question 5

When performing A-scan biometry, if the gain is set too high, what is the most likely measurement error that will occur?

Accepted Answer

An artificially elongated axial length due to retinal spike broadening.

Answer

An artificially shortened axial length due to corneal compression.

Answer

Inability to detect the posterior lens spike.

Answer

Failure to acquire any measurement due to signal noise.

Question 6

A Castroviejo caliper, though appearing physically intact, is suspected of being inaccurate. What is the most appropriate first step to verify its calibration in the clinic?

Accepted Answer

Measure a known distance on a standardized, high-quality ruler.

Answer

Send it to the manufacturer for professional recalibration.

Answer

Compare its readings against a new, out-of-the-box caliper.

Answer

Bend the needle points slightly to adjust the measurement.