VISUAL FIELD TESTING
How much we can see of the world around us is known as our visual field. Glaucoma first damages our visual field.
If you hold your vision on one spot you will be aware that everything in the centre is clear, but becomes less and less clear the further away from the centre an object is.
When we close one eye we see the world through an oval shaped hole which is referred to as our peripheral visual field. Because we have two eyes and a large percentage of our visual field is contributed to by both eyes seeing the same thing, it is possible to lose quite significant portions of our visual field and yet be unaware of it.
Visual field tests are designed to map a person’s visual field; to document the extent of peripheral vision. As most glaucoma patients know, the test consists of responding every time a flash of light is perceived while looking straight ahead.
If doctors relied only on a reduced visual field to detect glaucoma, they would miss most people with early glaucoma. That is why field-testing is only one part of a glaucoma evaluation. If doctors suspect a person may have glaucoma a visual field test may help confirm or rule out glaucoma. The visual field also provides essential information about whether the glaucoma is stable or is getting worse.