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 (globes).
How the Test is Performed:
A special dye, called contrast, may be injected into your hand or forearm before the test starts. Contrast can highlight specific areas inside the body, which creates a clearer image.
You will be asked to lie on your back a narrow table that slides into the center of the CT scanner. Only your head is positioned inside the CT scanner.
You may be allowed to rest your head on a pillow, but this must be done before the scan begins. It is very important that once your head is in place, you do not move it during the test. Movement causes blurred images.
Once inside the scanner, the machine’s x-ray beam rotates around you. (Modern “spiral” scanners can perform the exam in one continuous motion.)
Small detectors inside the scanner measure the amount of x-rays that make it through the part of the body being studied. A computer takes this information and uses it to create several individual images, called slices. These images can be stored, viewed on a monitor, or printed on film. Three-dimensional models of organs can be created by stacking the individual slices together.
Generally, complete scans take only a few minutes.
How to Prepare for the Test:
Remove dentures, any jewelry, and anything metal.
If contrast is used, you may be asked not to eat or drink anything for 4-6 hours before the test.
Some people have allergies to IV contrast and may need to take medications before their test in order to safely receive this substance.
How the Test Will Feel
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
- Nerves supplying the eyes (optic nerves)
An orbit CT scan may also be used to detect:
- Abscess (infection) of the eye area
- Hard-to-see fractures of the eye socket
- Foreign object in the eye socket