What is tunnel vision? Moderate and severe cases of peripheral vision loss create the sensation of seeing through a narrow tube, a condition commonly referred to as “tunnel vision.” Symptoms of peripheral vision loss also can include difficulty seeing in dim light and decreased ability to navigate while you are walking.

A common cause of loss of peripheral vision (also called a peripheral field defect) is optic nerve damage from glaucoma. Eye “strokes” (occlusions) that block normal blood flow to the eye’s internal structures, including the optic nerve, also can lead to loss of peripheral vision. A stroke or injury also may damage portions of the brain where images are processed, leading to blind spots in the visual field.

If you suspect you have lost peripheral vision, see your eye doctor for a comprehensive eye exam that includes visual field testing. If you have a sudden decrease in peripheral vision, see your eye doctor immediately. Sudden loss of peripheral vision may indicate a detached retina, which is a medical emergency that must be treated as soon as possible to avoid permanent vision loss.

Source: http://www.allaboutvision.com/conditions/peripheral-vision.htm