COT Tonometry and Keratometry 4

Question 1

The Schiotz tonometer measures IOP by the principle of:

Accepted Answer

Indentation depth of the cornea under a known weight

Answer

Schiotz tonometry measures how deeply a known weight indents the cornea; a softer eye allows greater indentation.

Question 2

What is the standard keratometry mire size that most manual keratometers measure?

Accepted Answer

Central 3 mm zone of cornea

Answer

Standard manual keratometers sample approximately the central 3 mm zone of the anterior cornea.

Question 3

Which IOP range is considered statistically normal in most adult populations?

Accepted Answer

10–21 mmHg

Answer

The statistically normal IOP range for adults is approximately 10–21 mmHg, though glaucoma can occur at any pressure.

Question 4

During keratometry, the technician notices the mires cannot be brought into focus at the standard working distance. The MOST likely cause is:

Accepted Answer

The corneal curvature is outside the instrument's measurable range

Answer

Very flat (post-LASIK) or very steep (keratoconus) corneas may fall outside the diopter range measurable by a standard manual keratometer.

Question 5

After instilling fluorescein for Goldmann tonometry, the mire semicircles appear very wide and thick. The technician should:

Accepted Answer

Ask the patient to blink to thin the tear film before retaking the reading

Answer

Excess fluorescein causes wide mires that make the endpoint harder to judge accurately; having the patient blink redistributes and thins the tear film.

COT - Certified Ophthalmic Technician Practice Test

COT - Certified Ophthalmic Technician Practice Test

COT Tonometry and Keratometry 4