Certified Ophthalmic Medical Technologist (COMT) Practice Exam

In contact or applanation A-scan, what can unintended compression of the cornea result in post-operatively?

1. Refractive hyperopia

2. Blurred vision

3. Unintended refractive myopia

4. Visual field loss

The correct answer is: Unintended refractive myopia

In contact or applanation A-scan ultrasound, the procedure applies a small amount of pressure to the cornea to measure its thickness and the eye's internal structures. However, this pressure can inadvertently compress the cornea, particularly if excessive force is applied during the procedure. Post-operatively, this unintended compression can lead to refractive changes in the cornea. Specifically, it can cause a shift toward refractive myopia, which is a condition where distant objects appear blurry while close objects can be seen clearly. This effect happens because the cornea can temporarily change its curvature due to the pressure, altering the eye's power in a way that mimics myopia. Essentially, the altered shape can result in an increased refractive error, causing light to focus in front of the retina rather than directly on it when viewing distant objects. This phenomenon is particularly important for practitioners to be aware of, as it can impact patient outcomes and vision correction strategies after surgery. Understanding how corneal compression during diagnostic procedures can lead to these unintended refractive changes is crucial in ensuring proper patient care and postoperative assessment.