The Difference Between an A Scan and B Scan

Jul 14, 2021 | Optometry

The Difference Between an A Scan and B Scan

If you are studying optometry, odds are you have heard of A and B scans. But you might be wondering what each does. Keep reading to learn what each scan does, their uses, and the difference between an A scan and B scan.

What Are A & B Scans?

A scan is short for amplitude scan, while B scan refers to the brightness scan. Both are ultrasound tests performed on the eye by an ophthalmologist. These tests measure various data about the eyes. An ophthalmologist will perform an A or B scan in order to get a better understanding of the condition of your eyes and assess whether you may have an injury, disease, or condition of the eye. After all, monitoring our eye health is very important, so it is best to catch these ailments as early as possible.

Uses for Each

An ophthalmologist uses an A scan to determine the length of the eye through ultrasound technology. The length of the eye is most often used to determine whether a patient has any sight disorders, such as cataracts. On the other hand, an ophthalmologist will use a B scan to diagnose other issues by comparing different parts of the eye, such as the lens, sclera, retina, and more. B scans help these structures come into view.


While ophthalmologists usually use both A and B scans to diagnose eye abnormalities, they do have their differences. A scans involve a one-dimensional examination of the eye, while B scans are multidimensional and allow various views of many different parts. Each scan also detects different abnormalities, which is why they are so successful in monitoring eye health when used together.

We hope this sheds some light on the difference between A scan and B scan and how both function together and separately. Overall, both methods are very effective for maintaining eye health, though they do have different realms of specialization. If you offer eye testing at your practice, make sure to visit Automated Ophthalmics, Inc. for the eye testing equipment you need, such as tonopen covers, tune-ups, and more.