The visual field test (Humphrey visual field test)

What is a visual field test?

The visual field is simply the wide area of the space in front of us. Without moving our eyes, we see not only what is straight ahead, but some of what is above, below, and off to either side. Most people are familiar with this as ""peripheral vision."" The entire area that we see is called the visual field.

Visual field test measures two things:

• How far up, down, left and right the eye sees without moving.
• How sensitive the vision is in different parts of the visual field.
  

What is the goal of the visual field test?

The goal of the test is to help the doctor find visual field defects that can be signs of different diseases in the eye, optic nerve and brain. The test finds early signs of diseases like glaucoma that damage vision gradually. Some people with glaucoma do not notice any problems with their vision, but the visual field test shows that peripheral vision is being lost. By repeating more visual field tests at regular intervals, doctors can also tell whether the patient is getting better or worse. A visual field test can also help the doctor find out more about the part of optic nerve and the brain. There are well-known patterns in the test results that help doctors recognize certain types of injury or disease.

How is the test performed?

There are several types of visual field tests, but they all have one thing in common: the patient looks straight ahead at one point and signals when an object or a light is seen somewhere off to the side. The most common visual field test is the Humphrey visual field test. The Humphrey visual field is a very advanced technique to measure the visual field and calculate results that aid in more accurate information about the visual field. The test is performed with a computerized equipment and requires cooperation of the patient. During the test the head is always in the same place. The instrument has a large central ""target"" for the patient to look at, so the center of the visual field can be kept steady. The instrument uses tiny spots of light to test vision, and the brightness and color of the light can be changed to measure the sensitivity of vision at each location. The tests have been given to thousands of healthy people, so the ""normal"" results are fairly well known. The instrument can compare each new test to these standards.