Peripheral vision is the part of the visual field used when looking out of the side of the eye. Eye diseases that destroy peripheral vision include glaucoma, which usually affects the elderly; retinitis pigmentosa, which begins to cause vision loss during early adulthood; and chorioretinitis, which is caused by infection. In addition, a detached retina often causes severe vision loss and ultimately blindness, and hemianopsias may cause blindness in part of the visual field.
About Glaucoma
Glaucoma is a disease that causes damage to the retina and optic nerve. The retina is the light-sensitive part of the eye that sends information to the brain through the optic nerve. Glaucoma is commonly caused by increased eye pressure, and is treated with medication to decrease the pressure. The photoreceptor cells called "rods," located in the peripheral part of the retina, are responsible for peripheral vision and are first to be destroyed by glaucoma. Left untreated, peripheral vision can deteriorate and result in "tunnel vision," where a person sees the world as though looking through a tube.
Retinitis Pigmentosa
Retinitis pigmentosa is hereditary, and there's no cure as of 2010. According to Bill Chapman, author of "Coping with Vision Loss," the most common symptoms result from the progressive destruction of the rods, although another form of the disease affects the cones first. Vision loss is gradual, taking years before vision is impaired. According to "Foundations of Low Vision," many individuals who have retinitis pigmentosa also develop myopia and cataracts, but are unlikely to develop glaucoma or retinal detachment.
Chorioretinitis
Chorioretinitis is an inflammation of the part of the retina called the "choroid." It usually occurs after an infection, and a history of autoimmune diseases or infections increases the risk of developing the condition. According to the University of Pittsburgh Medical Center, symptoms include pain, redness, blurred vision, light sensitivity and excessive tearing. Treatment includes anti-infective agents and systemic corticosteroids. After healing, there may be pigmentation, scarring and blind spots called "scotomas" in the peripheral field. However, vision may only be minimally affected if the scotomas are scattered throughout the visual field.
Retinal Detachment
Retinal detachment can be caused by trauma or disease. Conditions such as diabetic retinopathy and severe myopia, or nearsightedness, increase the risk of detachment, and it's more common in people who have a family history of detachment or have had cataract surgery. According to the National eye Institute, when the retina detaches, it is lifted or pulled from its normal position and, unless treated promptly, permanent vision loss or even blindness may result. The most common symptom is the perception of flashing lights or "floaters" which look like specks floating around. If only the peripheral retina pulls away, it can usually be reattached with minimal peripheral vision loss. But if the detachment includes the macula and the retina is pulled away from the choroid, then blindness may result.
Hemianopsia
Hemianopsia is a blindness or reduction of vision in half of a visual field usually caused by pressure from a tumor, stroke or trauma. According to LowVision.org, the severity of vision loss varies from only subtle decreases in sensitivity during visual field testing to being able to only detect light or motion. There are many variations of type and site of visual field loss. For example, people who have had a stroke typically experience the field loss on the same side in both eyes. In other words, they may not see with the right eye in the visual quadrant near the right ear and with the left eye in the visual quadrant near the nose. Other people may have visual loss only in the visual field quadrants near the nose or near the temporal sides of the head.
References
- Low Vision: Hemianopsia
- National Eye Institute: Facts About Retinal Detachment
- University of Pennsylvania Medical Center: Choreoretinits
- "Coping with Vision Loss"; Bill Chapman; 2001
- "Foundations of Low Vision"; Anne L. Corn and Alan J. Koenig; 2004
