By examining a person's peripheral vision, a visual field test can help us diagnose many different conditions ranging from ocular migraines to macular degeneration to glaucoma and even brain tumors. A visual field test consists of a series of lights flashing at varying intensities in random positions around the patient's peripheral vision, with some lights occasionally flashing in front. While looking straight ahead, the patient depresses a button every time they perceive a flash of light. Once both eyes have been tested, the pattern that results helps us determine potentially damaged areas of the retina, damage to the optic nerve or even the possibility of a greater problem such as a brain tumor. Should there be such a finding, an accurate visual field test can even help narrow the search for a potential tumor as it will often indicate a fairly specific locale based on the pattern of the results.
A visual field test evaluates the performance of the visual pathway. The visual pathway is the path the nerves from the eye take through the brain to get to the back of the brain where all the visual information from the eyes is processed. Since this pathway is so long, many problems in the brain can affect it and therefore affect vision.
Some of the diseases that affect the visual fields are:
- Optic nerve diseases and tumors
- Multiple Sclerosis
- Brain tumors or aneurysms
- Pituitary tumors
- Brain injury/trauma