Visual field test
Encyclopedia
A visual field test is an examination that may be performed to analyze a patient's visual field
. The exam may be performed by a technician in one of several ways. The test may be performed by a technician directly, with the assistance of a machine, or completely by an automated machine. Machine based tests aid diagnostics by allowing a detailed printout of the patient's visual field.
Other names for this test may include Perimetry
, Tangent screen exam, Automated perimetry exam, Goldmann visual field exam, or Humphrey field exam.
Reference: Siverstone, DE, Hirsch, J: Automated Visual Field Testing. Appelton-Century Croft. Norwalk, CT. 1986.
Offline self examination (free) is possible at: http://visual-field.com/PerimetrySoftwareDownload.aspx
Visual field
The term visual field is sometimes used as a synonym to field of view, though they do not designate the same thing. The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments", while 'field of view' "refers to the physical...
. The exam may be performed by a technician in one of several ways. The test may be performed by a technician directly, with the assistance of a machine, or completely by an automated machine. Machine based tests aid diagnostics by allowing a detailed printout of the patient's visual field.
Other names for this test may include Perimetry
Perimetry
Perimetry or campimetry is the systematic measurement of differential light sensitivity in the visual field by the detection of the presence of test targets on a defined background. Visual field testing can be performed clinically with confrontational field testing keeping the subject's gaze fixed...
, Tangent screen exam, Automated perimetry exam, Goldmann visual field exam, or Humphrey field exam.
Exam methods
Here is a list of techniques used to perform this test:- Confrontation visual field exam / Donder's test - The examiner will ask the patient to cover one eye and stare at the examiner. The examiner will then move her hand out of the patient's visual field and then bring it back in. The patient signals the examiner when her hand comes back into view. This is frequently done by an examiner as a simple and preliminary test.
- Tangent screen exam or Goldmann field exam - Here the patient is asked to sit 1 meter (approximately 3 feet) from a screen with a target on the center. The eye that isn't tested is covered during the exam. While the patient stares at the target the examiner will move an object toward the patient's visual field. The patient signals the examiner when the object comes into view. This exam allows the patient's visual field to be mapped.
- Automated perimetry exam - The patient sits in front of a concave dome with a target in the center. The eye that is not being tested is covered. A button is given to the patient to be used during the exam. The patient is set in front of the dome and asked to focus on the target at the center. A computer then shines lights on the inside dome and the patient clicks the button whenever a light is seen. The computer then automatically maps and calculates the patient's visual field. (See PerimetryPerimetryPerimetry or campimetry is the systematic measurement of differential light sensitivity in the visual field by the detection of the presence of test targets on a defined background. Visual field testing can be performed clinically with confrontational field testing keeping the subject's gaze fixed...
for details.)
Reference: Siverstone, DE, Hirsch, J: Automated Visual Field Testing. Appelton-Century Croft. Norwalk, CT. 1986.
Self examination
Various methods of self examination are available in situations where professional testing is not available. Online self examination is possible at www.testvision.org.Offline self examination (free) is possible at: http://visual-field.com/PerimetrySoftwareDownload.aspx