Visual Field Analysis
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.
Confrontation visual field exam / Donder's test - We will ask the patient to cover one eye and stare at the examiner. The examiner will then move his hand out of the patient's visual field and then bring it back in. The patient signals the examiner when his 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 - Today this method is commonly used for early detection of blind spots. The patient sits in front of an (artificial) small concave dome in a small machine with a target in the center. The chin rest on the machine and 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. Humphrey Field Analyzer (HFA) is one of the Automated perimetry exam with lights appear on a white background dome (white-on-white).