A visual field test is a procedure used to measure a person's peripheral vision and overall sight. During the test, patients look at a central point and indicate when they see lights or objects in their side vision. This helps detect any blind spots or vision loss that may indicate underlying health issues. The test is commonly used by eye doctors to diagnose conditions such as glaucoma, retinal diseases, or neurological disorders. It can be performed using various methods, including automated machines or manual techniques, ensuring accurate assessment of a person's visual field.