Automated Visual Field Testing (Perimetry)
What is Automated Visual Field Testing?
Automated visual field testing (perimetry) is a form of visual field testing performed by a machine that presents stimuli (points of light) at defined points in the visual field.
Visual field testing in glaucoma is a crucial tool used by eye doctors to assess how well a person can see across their entire field of vision. Glaucoma is a disease that damages the optic nerve, which is responsible for sending visual information from the eye to the brain. This damage can cause blind spots in your vision, often starting on the outer edges and gradually progressing inward if not managed.
How is Automated Perimetry performed?
Automated perimetry is performed sitting upright on a machine in the clinic. It is a non-invasive test that typically takes between 2.5 to 4 minutes per eye. The visual field is tested one eye at a time (monocular) or binocular (for driving assessments). Your chin is positioned on a chinrest and the eyes face a white bowl-shaped curved screen. While looking straight ahead at a fixed target, small points of light are projected onto the screen in random locations and varying in brightness.
Your task is to press a button whenever you see one of these lights, no matter how faint. This creates a map of your field of vision, showing areas where you may have trouble seeing.
What is Automated Perimetry used for?
Automated Perimetry is used to diagnose glaucoma and monitor its progression. It is often used in conjunction with retinal photography and OCT scanning. It is useful to screen for toxicity from medications such as hydroxychloroquine (Plaquenil). It is also helpful in the diagnosis of optic nerve and neurological conditions.
The results of visual field testing help your eye doctor monitor any changes in your vision over time. For people with glaucoma, these tests are especially important because they can detect subtle changes in vision that may not be noticeable otherwise.
Early detection and regular monitoring through visual field tests can help prevent further vision loss and guide treatment decisions to manage glaucoma effectively.
Overall, visual field testing is a painless and important part of managing glaucoma, allowing doctors to track the progression of the disease and help preserve your vision for as long as possible. If you have glaucoma or are at risk, regular visual field tests are crucial to protect your eyesight.
What are is an example of an automated visual field analyser?
Zeiss Humphrey Field Analyser (HFA)
The Humphrey Field Analyser is the gold-standard automated perimeter that is used by Ophthalmologists to measure the central and peripheral visual field.
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