The visual field test determines the extent of peripheral vision loss and detects eye diseases in the early stages.
Peripheral vision is the side vision that is used to detect and navigate obstacles in the environment, such as oncoming vehicles from a side street; while central vision is the fine vision people use to read and recognize faces. People often fail to notice loss of peripheral vision until it has progressed toward the center of vision. Unless an individual is examined by an eye doctor, they could be unaware they have a vision threatening disease.
Many eye diseases effect peripheral vision first. This means that an individual can have 20/20 visual acuity until the central vision is finally effected late in the disease progression. When central vision is effected, people notice a black (or blind) spot in their vision.
When vision is tested on the eye chart, only the central vision is being tested. Reading 20/20 on the eye chart would mean the individual has normal visual acuity. However, the eye chart does not test peripheral vision. The only way to effectively test peripheral vision is to have a computerized visual field test.
The visual field analysis is done by a computerized instrument called the Humphrey Field Analyzer. This test draws a map of the back of the eye and is one of the best methods to measure the visual field. The visual field test is used to detect eye diseases in the early stages, before most people notice any symptoms. This is an important step in preventing or slowing future vision loss.
Normal Visual Field Superior Vision Loss
Superior and Inferior Vision Loss End Stage Vision Loss