The Function of Peripheral Vision
Peripheral vision is largely used for localization and orientation. When a patient starts losing their peripheral vision, they become disoriented. It often feels like things sneak up on them or come out of nowhere.
Flawed Assumptions About Field Loss
Visual field loss is often portrayed in textbooks as black spots in the vision. This is misleading because it implies that a patient has a conscious awareness of where they are blind. For someone to see black spots, there would need to be debris inside the eye. The debris would obstruct the path of light to the retina, and broadcast a black spot to the visual cortex...much like a large floater.
With visual field loss, information never makes it back to the visual cortex, so it cannot be consciously seen. Nature has already provided us an excellent example of this. The physiological blind spot is a much better example of visual field loss. Check out our Physiological Blind Spot Test to simulate how visual field loss appears in reality.
Field loss is bizarre, and hard to fathom. Caregivers often don’t understand the implications. For homonymous hemianopsia, taping one side of the caregivers vision is an incredibly helpful demonstration. Maybe even try it on yourself if you’ve never done it before.