Field of vision test
What is the field of view or field of vision?
When you look ahead, you can usually see most of the space in front of you. Without moving our eyes, we see not only what is directly in front of us, but also what is above, below and to either side. Most people know this as ‘peripheral vision’. The whole area we see is called the field of vision.
Vision is usually best in the centre of the field of vision. . That’s why we turn our eyes towards objects we want to see better. The further an object is from the centre of our vision, the less clearly we see it. When an object moves far enough to the side, it disappears from our field of vision completely.
The visual field test looks at how far up, down, left and right the eye can see without moving and how sensitive the vision is in different parts of the visual field.
What is visual field loss and what are the symptoms?
Visual field loss is when any part of a person’s visual field is impaired. Visual field loss can occur both in the periphery and near the centre of vision.
In the case of central visual field loss, the patient often does not perceive anything at all because the visual field loss in one eye is compensated by the other eye. The loss of central vision can affect visual acuity, the ability to distinguish shapes and details in one’s vision. People with central vision loss often feel that they cannot see fine detail or see blurry spots in the centre of the visual field. As the underlying disease and the damage it causes progresses, the blurred spots eventually turn into dark or ‘blind’ spots. The individual may have difficulty reading or driving, especially if the increased blind spot reaches the centre of the visual field.
Greater visual field loss can usually be caused by various eye conditions. For example, visual field loss may be the first sign of damage caused by glaucoma, but it can also be caused by cataracts or macular degeneration.
Causes of central vision loss
Many eye diseases can cause central vision loss. Most of these affect the retina or macula.
- Age-related macular degeneration
A change in the macula (which can be atrophic or even thickening) in the central visual field, resulting in loss of vision and reduced visual acuity.
A visual field test is essential in the case of glaucoma, because an increase in intraocular pressure leads to damage to the optic nerve, early signs of which can be detected by this test.
Cataracts are one of the most common causes of vision loss among the elderly, with cataracts causing blurred vision. Cataracts can affect the entire field of vision.
- Diabetic retinopathy
In early stages, it causes blurred vision, floaters in the visual field and changes in colour perception. If left untreated, diebethic rhytonopia can lead to permanent vision loss.
Why do I need a visual field test?
A visual field test can help your doctor find early signs of diseases that are gradually damaging your vision, such as glaucoma. Some patients with glaucoma may not notice any vision problems, but a visual field test can show that peripheral vision has been lost.
A visual field test can also help the doctor to learn more about the part of the nervous system that allows us to see. The visual part of the nervous system includes the retina, the optic nerve and the brain itself. The visual part of the nervous system includes the retina, the optic nerve and the brain itself. Problems with any part of the system can alter the visual field. The test results show well-known patterns that help doctors identify certain types of damage or disease. By repeating several visual field tests at regular intervals, doctors can also tell whether a patient’s condition is getting better or worse.
How is a visual field test carried out?
A perimetre, or visual field device, is used to map the field of vision and the lesions in the field of vision. The visual field test is completely painless and does not require pupil dilation.
During the eye test, the field of vision is examined in one eye at a time, while the other eye is completely covered to avoid errors. During each examination, the patient must always look straight ahead to accurately map the peripheral visual field. Most modern visual field testing equipment continuously monitors fixation, or the patient’s ability to look straight ahead at all times.
The test is exciting, like a video game, as soon as you see a point of light, you have to press a button. By summing up your answers, the field of vision of the eye being tested can be drawn and any aberrations can be detected. The size of the lost area can be compared and traced, and important conclusions can be drawn from their extent.
In our vision center, we use the Opto AP300 automatic perimeter, which offers exceptional accuracy, speed and reliable results in visual field analysis.
Field of vision test
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