By: Matthew Wallace
A person’s ability to see is directly associated with minor and major aspects of his or her life. Despite its importance, good vision is something that is often taken for granted. At any stage of life, however, ones ability to see can diminish slightly or completely. When a person is unable to see clearly, even with corrective eye wear, it is known as a visual impairment. Vision impairment may be mild in some and extreme to the point of blindness in others. Although the term blind is most often used in reference to one’s inability to perceive light, blindness may also be partial.
With partial blindness, a person is able to see, but only to a limited degree. Even a person who can read the 20/200 line on an eye chart is considered blind, or legally blind. In some cases, a person who has a minor visual impairment may eventually worsen to the point that he or she is completely blind. In other cases, a visual impairment may never progress to that extreme.
Causes of Visual Impairment
Disease, genetics, disorders, and injury are all potential causes of visual impairment. Common eye conditions that result in visual impairment include glaucoma, cataracts, and macular degeneration. Systemic health conditions include high blood pressure, vitamin A deficiency in children, eye infections, HIV, and diabetes. For adults in the United States, a complication of diabetes known as diabetic retinopathy is the most common cause of blindness. In children, an eye condition known as amblyopia is the most prevalent cause of blindness.
The term “lazy eye” is often used in reference to amblyopia. Injuries to the eye may also result in visual impairment, particularly in people who do not otherwise have any eye or health problems. Injuries to the eye can occur as a result of vehicle or sports accidents. Projectiles from certain tasks may also result in vision impairing eye injuries. Congenital blindness occurs when a child is born without vision. This may be a result of an eye malformation, a maternal infection, or it may be inherited.
Who is at Risk?
Although anyone could potentially suffer from a vision impairment, the risk is higher for some people. A person’s age and a family history of blindness or other forms of visual impairment create a greater risk. Certain ethnic groups are more susceptible to conditions that may lead to blindness. For example, Caucasians are a group of people who are more likely to develop macular degeneration, while the risk of diabetic retinopathy is greater in Hispanics and African-Americans.
Even habits such as smoking can lead to visual impairment by increasing one’s risk of macular degeneration. People working in certain types of jobs are also at a greater risk of injuries that could impair their vision. Income level also contributes to higher risks of blindness and vision impairment. Lower income may prevent a person from having eye examinations that could detect early signs of potentially vision-threatening conditions.
It may also prevent a person from getting the appropriate medical care to treat conditions, such as diabetes that could detect certain conditions early. Children with the highest risk factors include children who are exposed to drugs and/or alcohol prior to birth, who are born prematurely, and who are victims of Shaken Baby Syndrome. Lack of or poor prenatal care can also cause blindness or reduced vision.
Prevention of Blindness
Taking steps to avoid the causes of blindness is the most effective way to prevent it. When working around objects that may become airborne and puncture the eye, people should wear protective eye wear. This includes performing certain chores or crafts in the home that involve cutting, sawing or drilling and when participating in sports. Regular eye examination can detect problems that may lead to blindness.
Certain health conditions are also detectable in the eye, such as diabetes. People with diabetes, high blood pressure and other health conditions should closely follow their doctors’ instructions for the treatment and care. If a person is a smoker, he or she should stop. Eating more healthfully, losing or maintaining a healthy weight will help to reduce the risk of developing diabetes. Changing one’s diet so that it consists of more fresh fruits, dark green leafy vegetables, omega-3 rich foods and whole grains and less refined and high unsaturated fats, may reduce the risk of macular degeneration.
In the United States, there are 21.5 million adults who are visually impaired, according to the American Foundation for the Blind. Of these people, 12.7 million are women and 8.8 million are men. In terms of income, 8.5 million people are poor, while 2.4 million have an income that is greater than $100,000.
On a global level, there are 285 million visually impaired people, 39 million of which are blind. Approximately 90 percent of these people are from developing countries. Worldwide, 80 percent of the cases of visual impairment could have been avoided with early detection and treatment. Although diabetic retinopathy is the primary cause of blindness for people living in the U.S., at 17.6 million people, cataracts are the main global cause.
According to the World Health Organizations (WHO), 65 percent of people who are 50 years old or older, are visually impaired. This is approximately 20 percent of the global population. Of children age 15 and younger, 19 million have some form of visual impairment. Studies show that every minute, a child somewhere in the world loses his or her sight. WHO also notes that the number of visually impaired people across the world has been declining since early in the 90s.
- World Health Organization: Visual Impairment and Blindness Fact Sheet – Key Facts
- TeensHealth: Visual Health
- Some Causes of Visual Impairment in Infants and Toddlers
- JAMA – American Medical Association: Causes of Visual Impairment
- Medline Plus: Blindness and Vision Loss
- Vision Loss Prevention Strategies
- Blindness and Visual Impairment Causes
- Daily Vitamins Could Prevent Vision Loss Among Thousands
- Preventing Vision Loss Due to Diabetes
- Blindness and Vision Loss Research
- Vision Impairment Warning Signs and Risks
- Signs of Eye Problems in Adults
- Avoiding Eye Injuries
- Leading Causes of Blindness
- American Foundation for the Blind: Facts and Figures on Adults with Vision Loss
- Blind Adults in America: Their Lives and Challenges (PDF)
- Lighthouse International: Prevalence of Vision Impairment