A visual field test is a method of measuring an individual's entire scope of vision, that is, their central and peripheral (side) vision. But first things first. What is the person's visual field, and what does the perimetry test cost?
You can also watch the video on how perimetry is done.
Let's say you are looking at the television. While looking at this television, can you see the lampshade next to the tv? Or something else lying next to the tv. Can you see the wall around the television? Mind you, you see these things despite looking directly at the television. That is your visual field.
So as mentioned in other parts of this website, glaucoma is when the eye pressure increases. This increased pressure over a prolonged period damages the optic nerve. The optic nerve has fibres from all over the retina, which means fibres responsible for your entire vision are present in the optic nerve. In glaucoma, certain fibres are damaged earlier than some others. The fibres responsible for peripheral vision are damaged before the fibres responsible for your central vision. If the fibres responsible for peripheral vision are damaged, your visual field is affected. In other words, if you are watching the television, you would be able to see the wall around the tv everywhere except the part above the tv, which means that the upper part of the visual field is damaged.
Since your visual field is damaged in glaucoma, the Visual field test helps detect the amount of damage and thus helps determine treatment.
The visual field test is done for two general conditions: glaucoma and specific neurological or brain or optic nerve issues.
Glaucoma, you have already been explained. You may understand that the optic nerve enters the brain and transfers information from our eyes to our brain. If there is any damage to these fibres in the brain, the person will have vision problems. When a visual field test is done in such a person, your treating doctor will locate the area in the brain where there is a problem by looking at the visual field test result.
The visual field test is done for glaucoma at the first visit when your doctor wants to confirm that you have glaucoma and as a follow-up investigation to know how much the disease has advanced. It would help your doctor decide if the treatment should be continued or changed.
The visual field test is a subjective examination. This means that we require the patient to understand the testing instructions, fully cooperate, and complete the entire test to provide helpful information. It is not like taking a picture of the eye but more like performing a test.
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