3.2 When Vision Fails |
| When ordinary eyeglasses or contact lenses cannot
correct an older person's vision, an eye disorder such as cataracts,
glaucoma, macular degeneration and diabetic retinopathy is usually
suspected. Each of these disorders affects vision in a different
way and, if untreated, will cause severe vision loss.
Cataracts
Cataracts are common among older people, and occur when the clear
lens of the eye loses its, transparency and does not allow light
to pass through.
Effect on Vision: Cataracts vary in size, thickness and
affect vision differently. Some people experience only a slight
disability. Others suffer a significant vision loss. With cataracts,
overall vision tends to become cloudy, as if one is looking through
a dirty windshield. Bright, glaring light and sunlight are also
particularly troublesome. People with cataracts frequently have
trouble reading because the print seems hazy and lacks contrast.
Colors may appear faded.
Effect on Behavior: When cataracts severely impair overall
vision, a person may be reluctant to leave familiar surroundings.
Driving and walking outdoors may become difficult. This, in turn,
can produce increased isolation. The diminished ability to distinguish
closely-related colors often make relatively simple household chores
arduous. When cataracts make reading difficult or impossible, many
daily activities are affected.
Treatment: With a success rate of 95%, surgical removal
of the lens of the eye is the most effective treatment for cataracts.
In most cases, an eye doctor will recommend a lens implant to provide
focusing power for the eye. Below are some suggestions for those
who have cataracts that cannot be removed or whose vision is impaired
before surgery.
Practical Suggestions:
- Increase the use of contrasting colors in a room.
- Reduce glare caused by sunlight and interior light reflecting
on shiny surfaces.
- Consider use of special lenses which block ultraviolet light
and make outdoor travel much easier.
- Suggest wearing a wide brim hat to prevent sunlight glare.
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Glaucoma
Glaucoma is a disease in which too much fluid accumulates in the
eye because of insufficient drainage. The excessive fluid causes
increased pressure in the eye, which eventually damages the optic
nerve. Glaucoma occurs most frequently in people over 40. It is
an insidious, symptom-free disease whose damage is usually not detected
until some vision has been irreversibly lost.
Effect on Vision: Slightly blurry vision may be a sign of
glaucoma. Loss of peripheral (side) vision is also characteristic.
Some people will experience sensitivity to glare, adapt slowly in
shifts from light to dark and vise versa, and may see poorly in
dim lighting situations.
Effect on Behavior: Persons with reduced peripheral vision
tend to have problems getting around. It is not unusual, for example,
for them to bump into things. When traveling outdoors, they may
have difficulty seeing the general flow of people, cars and objects,
and therefore may be reluctant to travel alone. People with advanced
glaucoma may also have difficulty reading because the print can
appear faded and blurred.
Prevention/Treatment: Vision loss due to glaucoma can be
prevented if the disease is detected and treated at an early stage.
Because there are rarely any symptoms, glaucoma is best detected
during a regular eye examination. If glaucoma is present, treatment
with eye drops, pills, laser or sometimes surgery will be recommended.
Glaucoma cannot be cured, but vision loss can be minimized or prevented
with proper treatment.
Practical Suggestions:
- Put household objects in designated places. A person with peripheral
vision loss may have trouble locating things or may knock over
objects which are in unfamiliar places.
- If necessary, teach scanning techniques for retrieving lost
objects.
- In work areas, keep all objects and materials in a confined
space.
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Macular Degeneration
Macular Degeneration is the leading cause of vision loss among
older people. The macula is a small area in the center of the retina
which enables us to read and to see small, fine detail. Macular
degeneration is a condition in which the macula deteriorates and
loses its ability to function efficiently.
Effect on Vision: Macular degeneration impairs central vision
but does not affect peripheral vision. Its early signs include:
blurring of reading matter, distortion of central vision on a dark
spot in the center of the visual field. Macular degeneration does
not cause total vision loss.
Effect on Behavior: Persons with macular degeneration may
be unable to see and recognize faces and perform detailed work,
such as reading and sewing. Sometimes they become depressed when
they feel that they can no longer do some of the things they enjoyed.
Rarely does a person with macular degeneration experience mobility
problems, but color vision may be affected.
Treatment: There is no cure for this disorder. However,
new techniques are being developed to detect and treat it at its
earliest stage. Consult an ophthalmologist for the latest update.
Practical Suggestions:
- Magnification is the most significant method to improve functional
ability. It can be achieved with optical devices which require
evaluation and prescription by a low vision specialist. Non-optical
devices such as large print are also effective in some cases.
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Diabetic Retinopathy
Diabetic Retinopathy is a complication of diabetes. The small vessels
that nourish the retina may weaken and leak blood into the eye's
clear liquid. Damage to the retina may also occur. Not all diabetics
develop retinopathy, but most people who have had diabetes for over
15 years have some blood vessel damage in their eyes.
Effect on Vision: The amount and type of vision loss vary
with the severity of blood vessel damage. Near vision may also be
affected, with print often appearing distorted or blurred.
Effect on Behavior: If central vision loss is severe, behavioral
changes will resemble those which occur in macular degeneration.
Frequently, people who have visual complications from diabetes experience
daily changes in their visual ability. Some days they can see better
than other days. This naturally raises a person's general anxiety
level.
Treatment: Diabetics must pay special attention to their
eyes. If diabetic retinopathy is diagnosed early, blindness can
usually be avoided. Laser treatments can effectively seal abnormal
blood vessels, thereby reducing vision loss. Proper control of
blood sugar levels can greatly help reduce visual complications.
Regular eye examinations by an ophthalmologist is the only way
to minimize the risk of severe vision loss due to diabetes.
Practical Suggestions:
- Have regular eye examinations.
- If there has been some loss of central vision, follow the suggestions
listed for macular degeneration.
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Low Vision
When eyeglasses, contact lenses, medical treatment and surgery
are unable to correct a person's sight, that person is said to have
low vision. People with low vision are not blind, but they cannot
see within the normal range. Among older people, low vision usually
results from one of the eye conditions already discussed. People
with this problem should be examined by an ophthalmologist or an
optometrist specially trained in low vision evaluation and prescription.
These clinicians may suggest low vision optical devices that magnify
an image or redirect the image to a healthy part of the retina.
Low vision optical devices help people to use their remaining vision
most effectively.
Magnification makes distant objects appear clearer or larger. High
powered spectacles, hand magnifiers, magnifiers that stand on a
page, or telescopic lenses may be recommended. Low-vision devices
cannot restore normal vision and are sometimes tedious to use. But
these lenses are often the only way an older person with vision
loss might be able to read the label of a medicine bottle or a letter
from a dear friend. A good low vision examination will include instruction
on the effective use of these devices.
If a person with the best corrective lenses cannot see more at
a distance of 20 feet than someone with normal sight can see at
200 feet, that person is considered legally blind. This definition
is used by most states and the federal government to determine eligibility
for income tax exemptions and special education and rehabilitation
services. Visually acuity of 2000, although called legal blindness,
is not solely an indicator that person functions poorly. Most legally
blind people function very well. |
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