Visual Impairment
Alternate Names : Impaired Vision
Visual impairment refers to sight that has less quality, strength,
or value than normal. Sight becomes weakened or damaged in some
way.
What is going on in the body?
Some people are born with visual
impairments. Vision changes can
also
occur in people of any age for a number of reasons, including conditions within
the eyes, as well as conditions within the brain. The change in a person's
sight may
be minor or severe. Vision problems can range from an inability to see certain
colors to blurred vision or complete loss of sight. The visual impairment may
be acute, meaning occuring suddenly, or chronic, which means that the visual
changes last for
a long period of time.
What are the causes and risks of the condition?
A person may be
born with visual impairments, or they may occur later in life. Common causes of
visual impairment include the following:
damage to the visual nerves, such as that caused by head injury,brain
tumor, or infection
diabetes
glaucoma, or abnormally
high pressure
inside the eye
injuries to the eye, such as
corneal
injuries
brain damage, such as that from a
stroke, or brain attack
refractive errors, which means that objects appear blurry only when
they are up
close or when they are far away. This is commonly known as being nearsighted or
farsighted. Nearsightedness, or myopia, means that objects that are far
away are
not seen clearly. Farsightedness, or hyperopia, means that objects that are
close are
blurry, while objects far away can be seen clearly. These conditions often are
the
reasons people need glasses.
color blindness, an
inherited
condition that is much more likely in males
macular degeneration, a
common cause
of poor sight in the elderly. This condition affects the retina, or
back of the eye, and occurs for unknown reasons.
cataracts, another common
cause of
poor vision in the elderly, although it can occur even in newborn babies
Cataracts describe a clouding of the lens, or focusing, part of the eye.
aging, which can cause
people to
need reading glasses or bifocals starting around the age of 40 or 50. This
condition is called presbyopia and is considered normal.
astigmatism, or blurred
vision in
only certain areas of sight, which is caused by abnormal bending of light
through the
eye
medication side effects, such as those from the heart medication
digoxin or
the antibiotic ethambutol
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