Peripheral vision refers to the sight that from the corner of the eyes while focusing on something that is placed right ahead of you. With age, your peripheral vision begins to weaken. Peripheral vision could also get weaker if the muscles around the eyes become weak. It is a healthy practice to get your peripheral vision checked from time to time.
For the peripheral vision test, the doctor will ask you to sit on a chair facing an alphabet chart and ask you to close one eye. You can do this by either placing your hand over the eye, or with the help of a device that you can hold with your hand. Your doctor will instruct you on how to do it. You will then have to look straight ahead and tell him if you see an object placed in the periphery even as you keep your eyes focused on an object placed ahead of you. This item could be anything, and may even be the doctor's hands or an object placed in the clinic. Some doctors also choose to hold up their fingers and ask you to define the number of fingers shown. Once you are able to see the object, tell the doctor so that he can identify whether you have lose peripheral vision. This is the first step in the examination for confrontational visual field. This is a non-invasive method of testing.
Your doctor may also use a machine to measure your peripheral vision. The automatic perimetry machine is used to perform this test. You will be shown some light flashes in and around your field of vision. You will have access to a button that you will have to press as soon as you are able to see the flash. Your responses are recorded and tests scores are developed. If you still have doubts on how to test peripheral vision, an electroretinogram is another method of testing the peripheral vision. This detects potential vision loss due to conditions such as glaucoma.
While the peripheral vision test machine is used in a doctor's clinic, you can make a rough estimate of your peripheral vision at home as well. The manual test can be used as a peripheral vision test at home. The perception of shape and color of objects in your peripheral vision can be different for different people. However, the peripheral vision test results are considered normal when you are able to see the object placed at least a 30 degree angle. If you are not able to see the object even at 30 degrees, you should visit a doctor.