Certified Ophthalmic Assistant Practice Exam

Applanation tonometry readings need to be multiplied by what number to obtain the mm Hg?

1. 5

2. 10

3. 20

4. 15

The correct answer is: 10

The correct approach to obtaining applanation tonometry readings in mm Hg involves recognizing the specific conversion factor associated with this measurement technique. Applanation tonometry measures intraocular pressure (IOP) by assessing the force required to flatten a predetermined area of the cornea. When performing this measurement, the readings obtained from the tonometer are not expressed directly in mm Hg. Instead, they must be multiplied by a set conversion factor to yield the pressure in millimeters of mercury (mm Hg). For standard applanation tonometry, this conversion factor is 10. Thus, when the readings are multiplied by 10, they are appropriately transformed into the clinically recognized unit of measurement for IOP, which is essential for accurate diagnosis and treatment planning in ophthalmology.