Visual field test
A visual field test is an eye examination that can detect dysfunction in central and peripheral vision which may be caused by various medical conditions such as glaucoma, stroke, brain tumours or other neurological deficits.
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.
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[edit] 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 Perimetry for details.)
Reference: Siverstone, DE, Hirsch, J: Automated Visual Field Testing. Appelton-Century Croft. Norwalk, CT. 1986.
[edit] 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.[1] Offline self examination (free) is possible at: http://visual-field.com/PerimetrySoftwareDownload.aspx
[edit] External links
- IXMUS Color Field Test for Macula and Optic nerve Disease
- MedicinePlus Medical Encyclopedia: Visual Field
- Understanding visual field testing
[edit] References
- ^ Damato, B.; Groenewald, C. (2003). "Multifixation campimetry on line: a perimeter for the detection of visual field loss using the internet". The British journal of ophthalmology 87 (10): 1296–1298. doi:10.1136/bjo.87.10.1296. PMC 1920763. PMID 14507769. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1920763.
