COT Tonometry and Keratometry 5

Question 1

Which type of tonometer is most appropriate for an uncooperative child or a patient who cannot be positioned at a slit lamp?

Accepted Answer

Rebound (iCare) tonometer

Answer

Rebound tonometers like the iCare require no anesthetic, minimal cooperation, and can be used handheld in any position.

Question 2

The refractive index assumed by most manual keratometers when converting radius of curvature to diopters is approximately:

Accepted Answer

1.3375

Answer

Most manual keratometers use a standardized keratometric refractive index of 1.3375 to convert corneal radius to diopters.

Question 3

What is diurnal variation of IOP, and when is IOP typically highest?

Accepted Answer

IOP varies throughout the day; typically highest in the early morning

Answer

IOP follows a circadian rhythm and is typically highest in the early morning hours, which can be clinically significant for glaucoma monitoring.

Question 4

When performing keratometry on a patient with dry eye, the technician observes mires breaking up quickly. The BEST approach is to:

Accepted Answer

Instill artificial tears, wait briefly, then reattempt measurement

Answer

A dry, irregular tear film disrupts the reflected mires; lubricating drops temporarily stabilize the tear film for a more accurate reading.

Question 5

Which statement about the Perkins tonometer is TRUE?

Accepted Answer

It is a hand-held version of Goldmann applanation tonometry

Answer

The Perkins tonometer is a hand-held applanation device that uses the same Goldmann applanation principle, useful for supine or pediatric patients.

COT - Certified Ophthalmic Technician Practice Test