Certified Ophthalmic Medical Technologist (COMT) Practice Exam

What factors affect the accuracy of Goldmann applanation tonometry?

1. Corneal shape, elasticity, rigidity, and corneal thickness

2. Ambient light levels and patient age

3. Measurement technique and equipment calibration

4. Patient's refractive error and previous surgeries

The correct answer is: Corneal shape, elasticity, rigidity, and corneal thickness

Goldmann applanation tonometry is a method used to measure intraocular pressure (IOP) and is influenced by multiple corneal factors. Corneal shape is critical because variations in curvature can affect how the pressure is transmitted through the cornea and how the tonometry results are interpreted. Elasticity and rigidity of the cornea also play significant roles, as they directly influence how the cornea responds to the pressure applied by the tonometer. For instance, a stiffer cornea might give a higher pressure reading than a more elastic one, even if the actual internal pressure is the same. Additionally, corneal thickness is an important consideration; thicker corneas tend to yield higher IOP readings than thinner corneas, due to the greater amount of tissue that the measurement has to account for. These factors combine to affect the accuracy of the IOP readings obtained through this technique. The other options touch on aspects related to patient circumstance or technique but do not directly address the intrinsic properties of the cornea that are fundamental to the accuracy of Goldmann applanation tonometry.