What to Expect from an A Scan or B Scan



About A Scan and B Scan Tests

Has your eyesight been frustrating you recently? Not being able to see clearly will do that. Our eye can suffer from many common eye conditions and to discern what’s wrong, ophthalmologists and optometrists have various tests at their disposal. Two of the eye exams that Marano Eye Care in New Jersey utilized are the A Scan and B scan. Read on to learn more about these tests, how they’re administered, and what conditions may necessitate their use.

What is an A Scan?

An A-scan is short for amplitude scan. It is a type of ultrasound biometry that is provides data on the eye’s length.  Determining eye length is crucial regarding many common sight disorders, including near-sightedness and far-sightedness. However, for these common conditions, traditional clinician exams are sufficient and far less invasive.

What is a B Scan?

Similar to the A-scan, a B-scan (or brightness scan) is used in ophthalmology to produce a two-dimensional cross section of the eye and its orbit. It is most commonly used when a basic clinical examination isn’t revealing enough information.

How Do Ultrasounds Work for the Eye?

All ultrasounds are based on how the physics of sound work. Sound is emitted in a parallel, longitudinal pattern (it moves vertically instead of directly across). When the sound contacts an object, it bounces back. When the soundwave returns to the ultrasound probe, it is converted into an electric signal. That electric signal can then be interpreted as an image on a monitor.

Due to its ability to penetrate solid surfaces, sound-based imaging has proven to be extremely helpful in a variety of professions, including construction, archaeology, surveillance and of course the medical world.

To control the depth of the image, ultrasounds change the frequency of the soundwave. Since the eye does not have much depth, very high frequencies are used; usually around 10 million Hertz (10 MHz) and up to 50 MHz. In comparison, the minimum frequency for an ultrasound is 20,000 Hz, or 20 KHz.

How is an A-scan or B-scan performed?

All A-scans and B-scans are performed in our Marano Eye Care offices. For A-scans, your eyes will be numbed with anesthetic drops. You will sit in a chair and place your chin on a chin rest and look straight ahead. The ultrasound wand will be placed on the front surface of the eye. For a B-scan, the eyelids are closed and a gel is applied prior to the probe’s use. You will likely be asked to move your eyes in multiple directions.

What Conditions May be Diagnosed by an A-Scan or B-Scan?

The functions of an A-scan are narrower than that of a B-scan. Generally, they are used in determining the length of the eye for the appropriate replacement lens in cataract surgery. Some tumors may also be found with an A-Scan.

Because B-scans measure the structure and orbit of the eye, they have the potential to reveal details on more conditions, including: vitreous hemorrhage; cancer of the retina, under the retina, and other parts of the eye; damaged tissue or injuries to the orbital socket; any foreign bodies in the eye; swelling; and retinal detachment.

Speed of the Test and Risks

Due to the minimal preparation that goes into these tests, and the way that ultrasounds work, the test is quick and results are as well. While A-Scans can be a little uncomfortable in concept, your eyes will be numb and therefore no discomfort should occur. However, because of the anesthetic drops, be very careful regarding touching your eyes before the numbness subsides. Contact with the eyes while numb can inadvertently lead to scratching the cornea.

A Scans and B Scans by Marano Eye Care

As with any part of the body, maintaining the health of your eyes is important towards your quality of life. If you’re experiencing new foreign, painful, or obstructive sensations within your eyes, do not delay. Contact Marano Eye Care in Livingston, Newark, Denville, or Cedar Knolls for an eye exam today.

Marano Eye Care
Marano Eye Care
Marano Eye Care has been a leader in the rapidly changing field of vision care, being one of the first practices to perform advanced laser cataract surgery. Dr. Matthew Marano and his staff offer decades of experience in eye care and surgeries. Contact us for inquiries about our services or request an appointment at one of our three New Jersey locations.
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