COT Tonometry and Keratometry 3

Question 1

Before performing Goldmann applanation tonometry, which topical agent combination is typically instilled?

Accepted Answer

Fluorescein and a topical anesthetic

Answer

Fluorescein stains the tear film to visualize the mires, and a topical anesthetic prevents reflex blinking and discomfort.

Question 2

In manual keratometry, irregular mire images (distorted or blurred rings) most commonly indicate:

Accepted Answer

Corneal irregularity such as keratoconus or scarring

Answer

Distorted or irregular mire reflections indicate an irregular corneal surface, which warrants further evaluation with corneal topography.

Question 3

What is the purpose of the biprism in a Goldmann applanation tonometer?

Accepted Answer

To split the fluorescein image into two semicircles for endpoint detection

Answer

The biprism splits the circular fluorescein ring into two semicircles that the examiner aligns to determine the applanation endpoint.

Question 4

Rebound tonometry (iCare) works on which principle?

Accepted Answer

Induction and rebound of a small probe that contacts the cornea momentarily

Answer

Rebound tonometry fires a small magnetized probe that briefly contacts the cornea; the deceleration and rebound speed are used to calculate IOP.

Question 5

When calibrating a Goldmann tonometer, the check weight is applied and the drum is set to 2 g. What result indicates the instrument is correctly calibrated?

Accepted Answer

The balance arm swings freely to the up-stop

Answer

Correct calibration at the 2 g check weight causes the balance arm to swing to the up-stop, confirming the spring tension is accurate.

COT - Certified Ophthalmic Technician Practice Test

COT - Certified Ophthalmic Technician Practice Test

COT Tonometry and Keratometry 3