CPO FREE CPO Tonometry Principles and Procedures Questions and Answers 2

Question 1

A patient who recently underwent a vitrectomy with an intravitreal gas bubble is scheduled for tonometry. Which of the following is the most critical consideration when measuring their IOP?

Accepted Answer

The IOP can fluctuate dramatically with changes in atmospheric pressure, such as changes in altitude.

Answer

Intravitreal gas bubbles expand or contract with changes in atmospheric pressure. An ascent in altitude causes the bubble to expand, which can lead to a significant and dangerous increase in IOP. A descent can cause the bubble to contract. This volatility is a primary concern for patients with gas bubbles.

Question 2

When performing Goldmann applanation tonometry on a patient with significant corneal scarring, the paraoptometric is most likely to encounter which issue?

Accepted Answer

Difficulty achieving clear, well-defined semicircular mires for an accurate measurement.

Answer

Corneal scarring creates an irregular surface, which distorts the applanated area and the resulting fluorescein mires. This makes it difficult to properly align the inner edges of the semicircles, leading to unreliable or unobtainable readings with Goldmann tonometry.

Question 3

A paraoptometric performs a calibration check on a Goldmann tonometer. At the '2' setting (20 mmHg), the feeler arm only begins to move when the dial is turned past 2.4. When turned back, it only moves again when the dial is below 1.6. What is the most likely immediate cause of this inaccuracy?

Accepted Answer

An internal mechanism that requires lubrication.

Answer

This 'sticking' behavior, where the feeler arm does not move freely at the correct calibration points, is a classic sign that the internal mechanical components of the tonometer are not moving smoothly. The most common reason for this is a lack of lubrication, which can often be resolved by cleaning and lubricating the instrument.

Question 4

Which of the following tonometry methods is theoretically LEAST affected by corneal biomechanical properties like thickness, rigidity, and curvature?

Accepted Answer

Dynamic Contour Tonometry (DCT)

Answer

Dynamic Contour Tonometry (DCT) is specifically designed to measure intraocular pressure largely independently of corneal properties. Unlike applanation tonometers that flatten the cornea, DCT uses a sensor tip with a contour-matched shape that rests on the cornea, minimizing its deformation and the influence of its biomechanical properties on the reading.

Question 5

A patient with nystagmus requires an IOP check. Which type of tonometer would be most challenging to use effectively on this patient?

Accepted Answer

Non-contact tonometer

Answer

Non-contact tonometry (NCT) requires the patient to remain very still and fixated on a target for the instrument to align properly and deliver the air puff to the central cornea. The constant, involuntary eye movements of nystagmus make achieving this precise alignment extremely difficult, often resulting in error readings or the inability to obtain a measurement at all.

(CPO) Certified Paraoptometric Practice Test

(CPO) Certified Paraoptometric Practice Test

CPO FREE CPO Tonometry Principles and Procedures Questions and Answers 2