Certified Ophthalmic Medical Technologist (COMT) Practice Exam

What type of evaluation does a diagnostic A-scan provide that is different from the standard A-scan?

1. Quantitative evaluation of tissue structure

2. Assessment of eye color

3. Measurement of intraocular pressure

4. Visual acuity assessment

The correct answer is: Quantitative evaluation of tissue structure

A diagnostic A-scan provides a quantitative evaluation of tissue structure by measuring the echo patterns produced by the different layers of intraocular structures, such as the cornea, lens, and retina. This technique uses ultrasound waves to determine the distances and densities of these structures, which are crucial in diagnosing various ocular conditions. The quantitative data obtained from the A-scan allows for precise measurements of eye structures, helping in the calculation of intraocular lens power before cataract surgery and in the assessment of eyes with abnormal anatomy. In contrast, the other choices do not pertain to the capabilities of a diagnostic A-scan. For instance, assessing eye color falls under the realm of visual examination rather than ultrasound evaluation. Measurement of intraocular pressure is typically performed with tonometry, not through A-scan ultrasound. Visual acuity assessment involves determining the sharpness of vision, which is evaluated using charts and other tools, separate from the quantitative structural analysis provided by the A-scan. Thus, the distinctive feature of the diagnostic A-scan is its role in providing quantitative evaluations of ocular tissue structures.