Peripheral Vision

Peripheral vision is obtained through the nerve cells located outside the center or the macula of the retina. These nerve cells enable the eyes to perceive objects and other movements outside the central visual field and the direct line of vision. While looking steadily towards a particular object or direction the eyes gaze on the central visual field or the main object of focus. However, other objects or non-central objects appear outside the area of the central visual field and can be perceived by the eyes. This vision is known as the peripheral or side vision.

Peripheral vision can be distinguished in three types, namely, far peripheral, mid-peripheral and near peripheral. Far-peripheral vision helps in seeing the objects existing at the edges of the visual field whereas mid-peripheral refers to vision in the middle of the visual field. Near peripheral, also known as "paracentral" vision, exists almost next or adjacent to the central area of gaze.

The researches confirm of human beings have weaker peripheral vision as compared to animals, especially when it comes to distinguish shapes and colors. This is due to a greater density of the receptor cells at the center of the retina, which becomes lowest at the edges. In addition, the rod cells and the cone cells, forming the two types of receptor cells, are not able to distinguish colors. They concentrate mostly on the center of the retina, the macula. The peripheral vision helps in detecting motions through the rod cells and is usually stronger at night or in the dark when faced with scarcity of colors and light, which reduces the functionality of the cone cells.

The loss of peripheral vision may occur due to several ocular or neurological disorders. Some of the most common causes of losing peripheral vision may include transient migraine, glaucoma, stroke, ischemic optic neuropathy, branch retinal vein and branch retinal artery occlusion. On the other hand, some of the uncommon and rare causes may be pituitary tumors, brain tumors and aneurysms, and gyrate atrophy, to name a few.