Visual Fields

What is a Visual Field?

This test helps Dr. Piemontesi detect and monitor glaucoma. Usually, the visual field test is taken once a year but depending on the severity of your glaucoma, your doctor may decide to check your visual field more frequently.(1)

A visual field test maps out what your world looks like to you. It measures the area of vision, or how wide of an area your eye can see. Glaucoma is often called “The Sneak Thief of Sight” because it usually is a painless process that mostly affects the peripheral, or side vision, first.

The visual field shows changes that are not noticed by the patient until the damage is severe. This is usually when 50% of the visual field is lost. Other diseases, such as cataract, stroke, macular degeneration and diabetes, can also influence the visual field. Dr. Piemontesi will take these possible effects on your exam when interpreting the results.

What to expect when having a Visual Field Test

It is important when taking this test that you concentrate on the fixation light in the centre and press the button when the blinking test light is seen with your side vision. If you move your eyes to follow or look for the blinking lights, it decreases the reliability of the test and the ability of your doctor to monitor your disease.

Areas that appear gray or black on the test results reflect areas in your vision that are blurred or missing. If your glaucoma remains uncontrolled, these areas will get darker and larger.

We have two different types of visual field machines: Humphery Field Analyzer and Humphery Matrix. Both machines consists of a centre fixation light and blinking test lights in your side vision.

Humphery Field Analyzer2

Humphery Field Analyzer

The Humphrey Field Analyzer is considered to be the gold standard when monitoring glaucoma. If your visual field is worsening, it could mean that your pressures are too high and further treatment is necessary to lower your eye pressure. This machine has the ability to monitor glaucoma by using Glaucoma Progression Analysis.

Humphery Matrix Perimeter

Zeiss Matrix Field

This visual field machine is important for screening and picking up early glaucoma. This visual field machine has a frequency double technology meaning it targets low redundancy ganglion cells; because these cells are sparsely populated, there is less compensation available to mask cell damage. In other words, it tests the large nerves allowing to pick up early glaucoma damage.

Sources:, Carl Zeiss Meditec Germany