Alternative names
Perimetry; Tangent screen exam; Automated perimetry exam; Visual field; Humphrey visual field exam

Definition
The visual field is the total area in which objects can be seen in the peripheral vision while the eye is focused on a central point.

How the test is performed

Confrontation visual field exam: A quick and basic evaluation of the visual field done by an examiner sitting directly in front of you. With one eye covered, you are asked to look at the examiner’s eye and tell when you can see the examiners hand.

Tangent screen exam: You will be asked to sit about 3 feet from a screen with a target in the center. You will be asked to stare at the central target and let the examiner know when you can see an object brought into your peripheral vision. The extent of your peripheral vision is mapped.

Automated perimetry: You sit in front of a concave dome and stare at a central target within the dome. A computer-driven program flashes small lights at different locations within the dome’s surface, and you press a button when you see the small lights in your peripheral vision. Your responses are compared to age-matched controls to determine the presence of defects within the visual field.

How to prepare for the test
Adults:
No special preparation is necessary for these tests.

Children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

 
• Toddler test or procedure preparation (1 to 3 years)  
• Preschooler test or procedure preparation (3 to 6 years)  
• Schoolage test or procedure preparation (6 to 12 years)  
• Adolescent test or procedure preparation (12 to 18 years)

How the test will feel
There is no discomfort with this test. Some visual field tests take a long time and may be tiring.

Why the test is performed
The test will detect any loss of peripheral vision and provide a map of that loss which will be helpful in diagnosing the cause.

Normal Values
The peripheral vision is normal in extent.

What abnormal results mean
Abnormal results may indicate diseases or central nervous system problems 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, hyperthyroidism (a condition where the thyroid produces an excess of hormones), hypertension, diseases of the pituitary gland, and multiple sclerosis.

Additional conditions under which the test may be performed:

 
• Glaucoma  
• Optic glioma  
• Stroke  
• Stroke secondary to cardiogenic embolism  
• Stroke secondary to carotid dissection  
• Stroke secondary to cocaine

What the risks are
The test has no risks.

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

Medical Encyclopedia

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.