The visual field test is an examination, in which the field of vision is examined in detail. The field of vision is the entire space that a person can see with one eye when looking straight ahead. At the sides of this field of vision, no fine details are perceived, but only larger objects or movements.
Many eye diseases (such as glaucoma) may cause defects in the field of vision, and sometimes the type of visual field defect is characteristic of a particular eye disease. A visual field test can also be performed in case of suspected neurological disorders.
The field of vision of a human is roughly an oval area right in front of us and is larger in width than in height. It is usually measured with the aid of the perimeter, a hollow hemisphere, whereby the eye of the test person is located in the center.
During the examination, the patient must look with one eye to a light in the center of a sphere or a flat surface, whereby the other eye is covered with a patch. The patient looks straight at the light in the middle, while each time subsequently brief flashes are offered at various places, which the patient must respond to. The patient must press a button or say ‘yes’ when he or she sees a flash of light. Thus, the entire field of vision can be examined and the doctor can detect whether defects are found anywhere in the visual field.
Visual field test is a difficult examination, that requires a high level of concentration, otherwise it results in unreliable or incomplete information. The test is painless, there's no need to be instilled and it takes about 15 to 30 minutes per eye.