Definition of Eye and orbit ultrasound:

An eye and orbit ultrasound is a test to look at the eye area, and to measure the size and structures of the eye.

How the test is performed:

The test is usually done in the ophthalmologist's office or the ophthalmology department of a hospital or clinic.

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 about 15 minutes.

There are two types of scans -- A-scan and B-scan.

For the A-scan:

• You will usually sit in a chair and place your chin on a chin rest. You will look straight ahead.
• A small probe with some oil on it 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.

For the B-scan:

• You will be seated and you may be asked to look in many directions. The test is usually done with your eyes closed.
• 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:

Your eye is numbed, so you shouldn't have any discomfort. You may be asked to look in different directions to improve the ultrasound image or so it can view different areas of your eye.

A lubricant placed on the ultrasound wand may run on your cheek, but you won't feel any discomfort or pain.

Why the test is performed:

Your doctor may order this test if you have cataracts or other eye problems.

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 can't be seen directly. This may occur when you have cataracts or other conditions that make it hard for the doctor to see into the back of your eye. The test may help diagnose retinal detachment, tumors, or other disorders.