In order to measure the peripheral vision loss , visual field testing is conducted which should be repeated at regular intervals to determine whether the vision loss has progressed or is constant. Visual field would be a routine part of your treatment if you have a certain problem or disease, such as glaucoma.
Visual field testing can be done in a clinical examination by asking the patient to gaze at a point and focus on it, while moving an object like a pen in different positions in his visual field. In this examination, the angle that a person is able to see and percept the object is considered his visual field. When computers are used for testing, the diagnosis will be accurate and reliable. The machine test is measured by a device called perimeter or a hemisphere, in which the light points glow on a white surface.
Humphrey field analyzer is the most common perimeter method, in which 24 ° or 30 ° central test patterns in the visual field are often used more.
In principle, visual field testing contributes the ophthalmologist diagnose ocular, nervous, or brain problems, which include:
• Vision loss
• Glaucoma
• Retinal problems (a layer of cell located behind the eye)
• Other neurological (neural) conditions, namely, brain tumors, MS and increased intracranial pressure
Visual field test procedure
A large and bowl shaped instrument called perimeter device is used to conduct this test. Each time, one of your eyes is temporarily covered in order to test. You sit in front of the device, on the chair, and asked to look straightly to a fixed point (fixed target). The device randomly shines bright spots. When you see a light, press the cursor button. During the test, it is crucial to look at the orange color and keep your head steady. Do not look for the light spots with your eyes, wait until they appear in your peripheral visual field.