leading Causes of Vision Loss
The breaking down, or degeneration, of the macula area of the retina of the eye.
Age-related macular degeneration (AMD) is a disease that affects an individual’s central vision. AMD is the most common cause of severe vision loss among people over 60. Because only the center of vision is affected, people rarely go blind from this disease. However, AMD can make it difficult of read, drive, or perform other daily activities that require fine, central vision.
AMD occurs when the macula, which is located in the center of the retina and provides us with sight in the center of our field of vision, begins to degenerate. With less of the macula working, central vision – which is necessary for driving, reading, recognizing faces, and performing close-up work – begins to deteriorate.
There are two primary types of Macular Degeneration:
Dry macular degeneration
This type of MD is the most common. While its cause is unknown, it occurs as the light sensitive cells in the macula slowly deteriorate, generally occurring in one eye at a time.
Wet macular degeneration
This type of MD is less common, but accounts for almost all severe vision loss caused by either type of MD. Wet MD occurs when new blood vessels behind the retina start to grow beneath the retina where they leak fluid and blood and can create a large blind spot in the center of the visual field. If this happens, there is a marked disturbance of vision in a short period of time
Diabetic retinopathy is the most common eye disease in persons with diabetes.
Diabetic retinopathy is the leading cause of blindness in American adults. It is caused by changes in the blood vessels of the retina. In some people with diabetic retinopathy, retinal blood vessels may swell and leak fluid, while in others, abnormal new blood vessels grow on the surface of the retina. These changes may result in vision loss or blindness.
Diabetic retinopathy cannot be completely avoided, but the risk can be greatly reduced. Better control of blood sugar level slows the onset and progression of retinopathy and lessens the need for laser surgery for severe retinopathy.
Floaters, blurriness, dark areas of vision
Who is at risk for diabetic retinopathy?
Anyone with diabetes is at risk for diabetic retinopathy. The longer a person has diabetes, the more likely it becomes that he or she will develop diabetic retinopathy.
Can diabetic retinopathy be prevented?
Although diabetic retinopathy cannot be prevented, the risk of developing it can be reduced by:
having a dilated eye examination once a year
strictly managing your diabetes
Glaucoma is a condition in which the normal fluid pressure inside the eyes slowly rises as a result of the fluid aqueous humor – which normally flows in and out of the eye – not being able to drain properly. Instead, the fluid collects and causes pressure damage to the optic nerve.
While physicians used to think that high intraocular pressure (also known as ocular hypertension) was the main cause of optic nerve damage in glaucoma, it is now known that even persons with normal intraocular pressure can experience vision loss from glaucoma. Thus, the causes are still unknown.
What are the risk factors for glaucoma?
Although anyone can develop glaucoma, some people are at higher risk than others. The following are suggested as risk factors for glaucoma:
Race Glaucoma is the leading cause of blindness for African Americans.
Age Persons over age 60 are more at risk for developing glaucoma.
Family history People with a family history of glaucoma are more likely to develop the disease.
High intraocular pressure Persons with an elevated (greater than 21 mm Hg) intraocular pressure (IOP) are at an increased risk.
A cataract is a clouding or opaque area over the lens of the eye – an area that is normally transparent. As this thickening occurs, it prevents light rays from passing through the lens and focusing on the retina – the light sensitive tissue lining located in the back of the eye. This clouding is caused when some of the protein which makes up the lens begins to clump together and interferes with vision.
In its early stages, a cataract may not cause a problem. The cloudiness may affect only a small part of the lens. However, the cataract may grow larger over time and affect more of the lens, making it harder to see. As less light reaches the retina, it becomes increasingly harder to see and vision may become dull and blurry. While cataracts cannot spread from one eye to another, many persons develop cataracts in both eyes.
What are the risk factors for cataracts?
Possible risk factors for cataracts include:
Age Probably the greatest risk factor for cataracts is age. And, although age-related cataracts may develop between 40 and 50 years old, vision is usually not affected greatly until after age 60.
Geographic location Recent studies have shown that people who live in high altitudes are more at risk for developing a cataracts.
Excessive sun exposure Person who spend more time in the sun may develop cataracts earlier than others. The American Academy of Ophthalmology now recommends wearing sunglasses and a wide brimmed hat to lessen exposure to ultraviolet rays.
Retinitis pigmentosa (RP) refers to a group of inherited diseases causing retinal degeneration. The cell-rich retina lines the back inside wall of the eye. It is responsible for capturing images from the visual field. People with RP experience a gradual decline in their vision because photoreceptor cells (rods and cones) die.
Symptoms depend on whether rods or cones are initially involved. In most forms of RP, rods are affected first. Because rods are concentrated in the outer portions of the retina and are triggered by dim light, their degeneration affects peripheral and night vision. When the more centrally located cones – responsible for color and sharp central vision – become involved, the loss is in color perception and central vision. Night blindness is one of the earliest and most frequent symptoms of RP.
Gradual loss of peripheral vision. This is known as “tunnel vision.”
How is RP diagnosed? RP is typically diagnosed in adolescents and young adults. It is a progressive disorder. The rate of progression and degree of visual loss varies from person to person. Most people with RP are legally blind by age 40, with a central visual field of less than 20 degrees in diameter. It is a genetic disorder and, therefore, is almost always inherited.
How is RP inherited? An estimated 100,000 people in the U.S. have RP, mainly caused by mutated genes inherited from one or both parents. If a family member is diagnosed with RP, it is strongly advised that other members of the family also have an eye exam by a physician who is specially trained to detect and treat retinal degenerative disorders.