A-mode is used extensively in _______.

• A. Ophthalmology
• B. Cardiology
• C. Neurology
• D. Dermatology

Answer: (A)

A-mode ultrasound provides a one-dimensional readout of depth, showing tissue interfaces as vertical spikes along a single axis. The key idea is that it measures how far each interface is from the transducer by recording the time it takes for echoes to return, giving precise distance measurements.

In the eye, accurate axial length is crucial for calculating the power of an intraocular lens implanted during cataract surgery. The eye is effectively a straight, short path from the cornea to the retina, so a single-depth trace along that axis yields highly precise measurements of the eye’s length. This makes A-mode especially well suited for ocular biometry, where exact depth measurements directly impact surgical outcomes.

Other fields typically rely on two-dimensional imaging to visualize complex structures or to assess motion and flow, rather than focusing on a single depth measurement, which is why A-mode is most associated with ophthalmology.