Hallucinations often appear first in peripheral vision because of how our eyes and brain process visual information differently across the visual field. The peripheral vision—the area outside the direct line of sight—is more sensitive to motion and less detailed than central vision, which focuses on sharp, clear images.
When hallucinations occur, especially visual ones, they tend to emerge in the peripheral areas because these regions have a different neural wiring and are more vulnerable to disruptions or “noise” in the visual system. The brain constantly fills in gaps or interprets incomplete signals from the eyes, and this process is more prone to errors in the peripheral vision where the input is less precise.
In conditions like Charles Bonnet Syndrome, which happens when people lose some vision, the brain tries to compensate for missing visual information by creating images. Since central vision is often impaired first (such as in macular degeneration), the brain’s “filling in” activity starts in the peripheral vision, where the visual input is weaker or absent. This can cause hallucinations to appear in the side vision before affecting the center.
Additionally, the peripheral retina has a higher density of certain types of cells and connections that might be more easily triggered by abnormal brain activity or sensory deprivation, leading to hallucinations appearing there first. This is also why simple visual disturbances or flashes sometimes show up in the edges of vision when there are issues with the optic pathways or brain areas responsible for vision.
In short, hallucinations may appear first in peripheral vision because that part of the visual system is less detailed, more sensitive to irregular signals, and often the first to experience reduced input or disruption, prompting the brain to generate false images in those areas.
