Definition of Orbit CT scan:

A computed tomography (CT) scan of the orbit is an imaging method that uses x-rays to create detailed pictures of the eye sockets (orbits) and eyes.

See: CT scan

How the test is performed:

You will be asked to lie on a narrow table that slides into the center of the CT scanner. Only your head is placed inside the CT scanner.

You may be allowed to rest your head on a pillow, but this must be done before the scan begins.

Once you are inside the scanner, the machine's x-ray beam rotates around you. (Modern "spiral" scanners can perform the exam without stopping.)

A computer creates separate images of the body area, called slices. These images can be stored, viewed on a monitor, or printed on film. Three-dimensional models of the body area can be created by stacking the slices together.

You must be still during the exam, because movement causes blurred images. You may be told to hold your breath for short periods of time.

The scan should take only 10-15 minutes.

How to prepare for the test:

Certain exams require a special dye, called contrast, to be delivered into the body before the test starts. Contrast helps certain areas show up better on the x-rays.

• Contrast can be given through a vein (IV) in your hand or forearm. If contrast is used, you may also be asked not to eat or drink anything for 4-6 hours before the test.
• Let your doctor know if you have ever had a reaction to contrast. You may need to take medications before the test in order to safely receive this substance.
• Before receiving the contrast, tell your health care provider if you take the diabetes medication metformin (Glucophage) because you may need to take extra precautions.

If you weigh more than 300 pounds, find out if the CT machine has a weight limit. Too much weight can cause damage to the scanner's working parts.

You will be asked to remove jewelry and wear a hospital gown during the study.

How the test will feel:

Some people may have discomfort from lying on the hard table.

Contrast given through an IV may cause a slight burning sensation, a metallic taste in the mouth, and a warm flushing of the body. These sensations are normal and usually go away within a few seconds.

Why the test is performed:

This test is helpful for diagnosing diseases that affect the following areas:

• Blood vessels
• Eye muscles
• Eyes
• Nerves supplying the eyes (optic nerves)
• Sinuses

An orbit CT scan may also be used to detect:

• Abscess (infection) of the eye area
• Broken eye socket bone
• Foreign object in the eye socket