The visual field refers to the total area in which objects can be seen in the side (peripheral) vision while you focus your eyes on a central point.

Confrontation visual field exam: This is a quick and basic check of the visual field. The health care provider sits directly in front of you. You will cover one eye, and stare straight ahead with the other. You will be asked to tell when you can see the examiner's hand.

Tangent screen or Goldmann field exam: You will sit about 3 feet from a screen with a target in the center. You will be asked to stare at the center object and let the examiner know when you can see an object that moves into your side vision. This exam creates a map of your entire peripheral vision.

Automated perimetry: You sit in front of a concave dome and stare at an object in the middle. You press a button when you see small flashes of light in your peripheral vision. Your responses help determine if you have a defect in your visual field.

No special preparation is necessary.

There is no discomfort with this test.

This eye exam will reveal if you have a loss of peripheral vision and help your doctor diagnose the cause.

The peripheral vision is normal.

Abnormal results may be due to diseases or central nervous system disorders such as tumors that damage or compress the parts of the brain that deal with vision.

Other diseases that may affect the visual field of the eye include:

• Diabetes
• Glaucoma
• High blood pressure
• Multiple sclerosis
• Optic glioma
• Overactive thyroid (hyperthyroidism)
• Pituitary gland disorders
• Stroke
• Stroke secondary to cardiogenic embolism
• Stroke secondary to carotid dissection
• Stroke secondary to cocaine

The test has no risks.

The type of visual field testing to be done will be discussed with you by your doctor.