A visual field test assesses how much you can see in your peripheral (side) vision.  This test is used to detect early signs of glaucoma, or to help identify vision loss or other visual field defects due to inflammation of the optic nerve, retinal degenerative diseases, brain injury, stroke, or other neurological conditions.

Why is peripheral vision important?

Central vision allows you to see the fine detail in objects that you are viewing.  Peripheral vision is used to find objects, detect threats, and is important for general orientation and balance.

Peripheral vision is important for a number of tasks including reading.  If you have poor vision on the right side you may find it difficult to read a line of type, as you cannot see the next word in the line.  A person with poor vision on the left side may be able to read along the line but have difficulty finding the start of the next line.