Certified Ophthalmic Medical Technologist (COMT) Practice Exam

What distinguishes a "diagnostic" A-scan from an A-scan used for IOL calculations?

1. Diagnostic A-scan measures distance only

2. Diagnostic A-scan evaluates tissue structure and reflectivity

3. Both measure the same parameters

4. A-scan for IOL uses ultrasound only

The correct answer is: Diagnostic A-scan evaluates tissue structure and reflectivity

The distinguishing feature of a "diagnostic" A-scan is its ability to evaluate tissue structure and reflectivity. This method provides detailed information about the internal structures of the eye, such as the lens, retina, and other ocular tissues, by measuring how ultrasound waves reflect off different types of tissue. This reflectivity data helps in diagnosing various ocular conditions, as it reveals details about the composition and condition of the tissues. In contrast, the A-scan utilized for intraocular lens (IOL) calculations primarily focuses on measuring the axial length of the eye to calculate the appropriate lens power needed for surgical procedures, such as cataract surgery. While it utilizes ultrasound as well, it does not provide detailed information about tissue structure, making its application different from that of diagnostic A-scan measurements.