VISUAL FIELD TESTS
Visual Field tests
What – the process of determining the breadth of your field of vision. The test is painless but requires some concentration and is performed by a computerised machine. Usually it is performed upon each eye separately but sometimes both eyes are tested together (e.g. for the DVLA). The test lasts between 5-10 minutes per eye. All you need to do is to keep your head and eye still and stare straight ahead into a large white bowl. You will be required to press a button (in your hand) when you perceive any spots of light in the bowl, but do not go looking for them as this may invalidate the test. It is important that you do not see the test as a “challenge” or “competition” with the testing machine as there will be times when you are not sure whether you have seen a light or not – just be as honest with yourself and do the best you can.
Why - there are many reasons why your visual fields may need to be tested and your doctor will explain which is be relevant to you. The most commonly visual field tests are performed to both monitor and detect glaucoma, a process that can slowly damage the visual field, BUT visual field tests are performed routinely for many other reasons too.
Preparation – usually no specific preparation is required BUT try not to arrive feeling sleepy (e.g. after a night shift) and bring your normal distance / reading glasses with you.
Risk - there is no risk associated this testing. However, some patient’s can become a little anxious about the test, probably worrying about the results and whether they have done their best. Please try not to worry, the visual field machine is very clever, it knows that sometimes your responses will vary and its takes this and many other things into account.
How long will it take? – usually the process of testing visual fields takes between 15 and 20 minutes. But there may be a queue!