Peripheral vision, or side vision, is the wide-angle field of vision that appears beyond central vision. Loss of peripheral vision narrows the field of vision, giving the appearance of looking through a tunnel. The condition is often called "tunnel vision" or peripheral field defect. Other symptoms of tunnel vision are reduced vision in dim light and difficulty walking.
A sudden loss of peripheral vision can indicate a stroke and requires immediate medical attention.
One cause of the condition is optic nerve damage resulting from glaucoma--a category of eye problems that result from a buildup of pressure inside the eye. Loss of peripheral vision is an early indication of glaucoma. Another cause is eye blockages, or occlusions, in the veins and arteries causing "eye strokes" that compromise peripheral vision. When blood flow to the eye is blocked, the retina and optic nerve fail to receive oxygen and nutrients.
Peripheral vision loss can also result from retinitis pigmentosa--degeneration of the retina; detached retina--in which the retina becomes separated from connecting tissue; injury or concussions; disease; or papilledema--swelling of the optic nerve head; and neurological damage. Eye "floaters"--black spots or thread-like webs inside the field of vision--can also result in loss of peripheral vision. A temporary loss of peripheral vision may result from high levels of adrenaline caused by panic, anger, stress, alcohol, or drugs. The temporary condition usually resolves itself.
A thorough eye examination from an ophthalmologist or optometrist can diagnose the cause of peripheral vision loss and determine appropriate treatment. If glaucoma is the cause, treatment can help the condition. A detached retina can be corrected by surgery.
While eyeglasses or contact lenses are not useful in treating loss of peripheral vision, a type of lens using prisms may be employed to expand the narrowed field of vision. Low-vision specialists can offer help with special devices used to accommodate such vision losses.