Ultrasounds – A scan, B scan

Eye and orbit ultrasound

Ultrasounds: Ascan, B-scan are the two most common form of Ultrasounds.   The Ascan, B scan are used frequently and are quick painless tests.  An eye and orbit ultrasound is a test to look inside and also to measure  the eyes .  Along with the complementary OCT {reviewed in another section}, these instruments act in concert to locate disease and to measure the size and structures of the eye.

How the Test is Performed: Ultrasounds – Ascan, B scan

Both tests are painless.  Your eye is numbed with medicine (anesthetic drops). The ultrasound wand (transducer) is placed against the front surface of the eye.

The ultrasound uses high-frequency sound waves that travel through the eye. Reflections (echoes) of the sound waves form a picture of the structure of the eye. The test takes a few minutes.

Ultrasounds – A scan, B scan


The A-scan is primarily used to measure the eye to determine the correct lens implant for cataract surgery.

You will usually sit in a chair and place your chin on a chin rest.

You will look straight ahead.

IOL Master:

Contact A scan:

A small probe is placed against the front of your eye.

The test may also be done with you lying back. With this method, a fluid-filled cup is placed against your eye to do the test.


 B-scan Ultrasound:

Uses high frequency sound waves to produce images of the internal eye structures. It is a helpful diagnostic tool when cataracts or corneal scarring prevents Dr. Duplessie  from viewing inside of your eye.  You will be seated and you may be asked to look in many directions. The test is usually done with your eyes closed. It takes seconds and is  totally PAINLESS.

A gel is placed on the skin of your eyelids. The B-scan probe is gently placed against your eyelids to do the test.

How to Prepare for the Test

No special preparation is needed for this test.

How the Test Will Feel

You will not feel any discomfort or pain.

Why the Test is Performed

An A-scan ultrasound measures the eye to determine the right power of a lens implant before cataract surgery.

A B-scan is done to look at the inside part of the eye or the space behind the eye that cannot be seen directly. This may occur when you have cataracts or corneal scarring that make it impossible for Dr. Duplessie to see the retina or optic nerve clearly.

This test is also used to diagnose retinal detachment, tumors, or other disorders.

Ultrasounds – A scan, B scan.  Normal Results

For an A-scan, the length of the eye are in the normal range.

For a B-scan, the structures of the eye and orbit appear normal.

Ultrasounds – A scan, B scan. What Abnormal Results Mean


A B-scan may show:

Retinal Detachment

into the clear gel (vitreous) the retina pulls away from the wall

Cancer of the retina

A tumor is shown

Damaged tissue or injuries in the bony socket (orbit) that surrounds and protects the eye

Foreign bodies

Pulling away of the retina from the back of the eye (retinal detachment)

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