Certified Ophthalmic Medical Technologist (COMT) Practice Exam

If pressure is exerted on the globe during applanation, what will this measurement produce?

1. An accurate measurement

2. A falsely low measurement

3. A falsely high measurement

4. No effect on measurement

The correct answer is: A falsely high measurement

When pressure is exerted on the globe during applanation, this typically produces a falsely high measurement of intraocular pressure (IOP). Applanation tonometry measures the pressure in the eye based on the force required to flatten a small area of the cornea. If excess pressure is applied to the globe, it can compress the eye more than normal, which can lead to an overestimate of the actual IOP. This is because the measurement is affected by factors like the rigidity of the cornea and the pressure applied during the test. If the globe is compressed with increased pressure before the actual measurement is taken, the instrument may register a higher pressure than what is truly present. This scenario highlights the importance of proper technique and the need to avoid additional pressure during applanation to ensure that the measurements of intraocular pressure are as accurate as possible.