Blindness

Blindness is, fortunately, a rare occurrence during adolescence. Legal blindness may range from a complete loss of vision, which is total blindness to impaired vision. Impaired vision of 20/200 qualifies for legal blindness. Legal blindness is further defined as correction of vision to 20/200 in the better eye or a visual field of twenty percent or less. Using the snellen eye chart, an individual with 20/200 vision will be able to see the letters at twenty feet distance where individuals with 20/20 or normal vision can see the same line and letters at two hundred feet. To understand a visual field of twenty percent or less, imagine looking through a toilet tissue tube with one eye. This restricts your visual filed to less than twenty percent. About ten percent of individuals who are diagnosed with legal blindness have a total loss of vision.

Who is likely to develop blindness?

The following are some of the causes of blindness in adolescents.

• Congenital reasons, that is the teen is born with the condition. Examples include cataracts which are opacities in the lenses of the eyes, glaucoma which is an abnormally high pressure of the fluid inside the eye, brain defects and high pressure on the brain that is termed hydrocephalus
• Infections including encephalitis, meningitis and infections of the retina of the eye
• Neurofibromatosis and related diseases
• Eye tumors such as retinoblastoma and tumors of the optic nerve
• Degenerative diseases of the nervous system including atrophy of the optic nerve
• Leukemia with involvement of the central nervous system
• Injury including that from pellet guns, explosions, fireworks and caustic substances as well as injury to the brain or nerves connecting the eye to the optic lobe of the brain

When a person is blind from birth, then usually there is a developmental malformation, damage due to a congenital infection, birth injury or a genetically determined disease that can affect the eye or the visual pathways. Cataracts may occur around birth and retinoblastoma is usually found early in life.

Blindness, which develops in an adolescent who had useful vision, may happen, of course, due to injury. Tumors, infection and degenerative disease of the brain may occur during the adolescent years.

Another important cause of blindness in adolescents and young adults is retinitis pigmentosa (RP). This is a group of inherited diseases affecting the retina and characterized by a breakdown and degeneration of the photoreceptor cells. The retina lines the back of the eye and contains rods and cones. Together, these cells are responsible for converting light into electrical impulses. These impulses are transferred by the optic nerves to the optic lobe of the brain where they are converted to visual images. RP symptoms are often recognized in adolescence. It may be inherited by three different pathways from a parent.

Some children may not realize the severity of vision loss if it is a very slowly progressive problem. Of course, deterioration in school performance, difficulty in recognizing people, change in personal appearance and bumping into objects may be symptoms of blindness. Finding light to bright or too dim, squinting to see or disorientation may be clues that a teen’s vision is seriously disturbed.

Any significant loss of vision requires a prompt and thorough ophthalmic evaluation by an eye specialist. Neurological evaluation, imaging, and metabolic or genetic studies may also be indicated. The primary care clinician may be involved with the evaluation and other specialists may be called on as necessary.

The treatment for blindness will depend on the cause. If there is a tumor causing blindness, then that should be treated. Or if glaucoma is causing the loss of vision, then that condition must be evaluated and treated.

Adolescents who are legally blind face many issues. Academics will be affected by the degree of the teen’s impairment. The Americans with Disabilities Act helps those individuals with significant disabilities in the school and workplace. Everyday life activities including dressing, driving, dating, body image, exercise, meeting with friends, travel, reading the newspaper and watching television, videos or movies are all affected by blindness.

There are products for teens with low vision. Some of the adaptive equipment includes Braille translation software, large print printers, text to speech software and voice recognition software. Text to speech software converts text on a computer screen into spoken words and voice recognition software will convert the spoken word into text and commands that the computer will recognize.

Braille is a system where blind individuals can learn to read and write. It uses six dots and all numbers, letters and shorthand symbols can be created utilizing these dots.

Beside schools for the blind, there are many other agencies to assist the blind.

Some of these include the following:

      American Council of the Blind www.acb.org

      American Foundation for the Blind www.afb.org

      United States Association of Blind Athletes www.usaba.org

Sometimes blindness cannot be prevented. For example, if it is congenital, it may not be preventable. Before rubella vaccine was discovered, some children whose mothers had rubella during their pregnancy were born with blindness. Now all pregnant females should be immune to rubella by either vaccination or history of the illness. Or some children who acquired gonorrhea at birth from their mother became blind prior to the discovery of penicillin. Now all babies are administered antibiotics in their eyes to kill off the gonorrhea microorganism before it can produce an infection.

Using safety glasses during chemistry class to ward off possible injuries from chemicals may prevent blindness. Shooting pellet guns in an unsafe manner or at another individual is strictly off limits.

There are also some diseases that could lead to blindness. Adolescents who have type 2 diabetes mellitus may develop low vision or legal blindness. This occurs especially when the teen does not manage his or her blood sugars well. Although glaucoma is a much less frequent illness in adolescents than diabetes, it is very important that the teen with glaucoma take his or her medications as prescribed. Otherwise blindness could occur. And for any adolescent who has a chronic illness where blindness could be an end result, then follow up visits with his or her clinician are really important.

Related topics:

Academics, accidents, athletic equipment, chronic illness, dating, diabetes, disabilities, exercise, eye problems, fireworks injuries, neurofibromatosis, risk-taking, sports, travel