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You may be pleased to hear that you
have 20/20 vision and think you have perfect vision. But do you? Not necessarily. 20/20 only indicates
how sharp or clear your vision is at a distance. Overall vision also
includes peripheral awareness or side vision, eye coordination, depth
perception, focusing ability and color vision. 20/20 describes normal visual clarity
or sharpness measured at a distance of 20 feet from an object. If you
have 20/20 vision, you can see clearly at 20 feet what should normally
be seen at that distance. If you have 20/100 vision, it means that you
must be as close as 20 feet to see what a person with normal vision can
see at 100 feet. Is
25/25 vision better than 20/20? No. 25/25 means normal sharpness of
vision, or visual acuity, at 25 feet just as 20/20 indicates normal
vision at 20 feet. Why
do some people have less than 20/20? The ability to see objects clearly is
affected by many factors. Eye conditions like nearsightedness,
farsightedness, astigmatism or eye diseases influence visual acuity.
Most people with vision slightly below 20/20 function very well, whereas
some people who have better than 20/20 vision feel that their vision is
not satisfactory. Everybody's visual expectations are different and
satisfactory vision is far more complex than just being able to see
20/20. If
my vision is less than optimum, what can I do? A comprehensive eye examination will identify causes that may affect your ability to see well. We may be able to prescribe glasses, contact lenses or a vision therapy program that will help improve your vision. If the reduced vision is due to an eye disease, the use of ocular medication or other treatment may be needed. If necessary, referral will be undertaken if an eye disease is found which warrants further investigation. About 80 percent
of all babies are born farsighted—able to see objects clearly at a
distance but less clearly close up. Some five percent are born
nearsighted, or unable to see objects at a distance clearly. Approximately 15 percent are born
with nothing wrong with the refractive parts of the eye—the cornea and
crystalline lens which bend light and focus it properly on the retina.
Farsightedness usually decreases as a child ages, typically normalizing
to a negligible value by the age of 7-8. After a child grows and the incidence
of farsightedness decreases, that of nearsightedness increases. Many
school-age children and teens first discover they are nearsighted when
they have difficulty reading the writing on the board at school.
Nearsightedness usually occurs before age 25. Vision
skills for school Your school-age child's eyes are
constantly in use in the classroom and at play. When his or her vision
is not functioning properly, learning and participation in recreational
activities can suffer. Good vision involves many different skills working together to enable
your child not only to see clearly but also to understand what he or she
sees. Those skills include: Near Vision: Ability to see clearly and comfortably at 13-16 inches, the
distance at which school deskwork should be performed. Back
to School Distance Vision: Ability to see
clearly and comfortably at 10 feet or more. Why
thorough vision examinations are important Don't assume your child has good
vision because he or she passed a school vision screening. A 20/20 score
means only that your child can see at 20 feet what he or she should be
able to see at that distance. It does not measure any of the other
vision skills needed for learning. Vision screenings are important but
they should not be substituted for a thorough vision examination. Things
you can do There are things you can do to help
ensure that your child's vision is ready for school each year and to
relieve the visual stress of schoolwork. Be alert for symptoms that may
indicate your child has a vision problem. Note if your child frequently:
Make sure your child's homework area
is evenly lighted and free from glare. Furniture should be the right
size for proper posture. During periods of close concentration, have
your child take periodic breaks. Rest breaks are also recommended when
your child is using a computer or playing video games. To
make TV viewing easier on your child's eyes:
Teach
your child eye protection through these safety rules:
Thorough
vision care is important Because
a change in vision can occur without you or your child realizing it,
have your child's eyes examined every year. A
thorough eye examination should include:
If
your child's eyes need help After assessing your child's test
results, glasses, contact lenses or vision therapy may be prescribed. He
or she may also recommend preventive measures, such as mild prescription
lenses to be worn only when doing schoolwork or watching television.
These may help relieve stress on your child's eyes. Vision therapy is prescribed for
conditions that cannot adequately be treated with glasses or contact
lenses alone. By reinforcing or re-teaching vision skills, conditions
such as poor eye coordination and movement, lazy eye and perceptual
problems can be improved. Your care and concern for your child's vision can enrich his or her future while helping develop eye care habits for a lifetime of good vision. Eye care experts generally agree:
Watching television will not harm your eyes or vision if the TV room is
lit properly and if you follow a few viewing tips. In fact, there is
usually less strain involved in TV viewing than in doing close work such
as sewing or reading. But TV watching for long stretches of time can
leave your eyes fatigued. What
are the best conditions for TV viewing? A normally lit room, suitable for
general activities, is best. Excessively bright lighting tends to reduce
contrast on the screen and "wash out" the picture. No lights
should be placed where glare or reflections will be seen in or near the
television screen. Strongly colored lighting should not be used and
surroundings should be neutral in color. Is
it alright to watch television in a dark room? This situation is not ideal. When the
room is totally dark, the contrast between the television screen and the
surrounding area is too great for comfortable and efficient vision. When
the room is softly illuminated, undesirable high contrast is kept to a
minimum. Is
it better to adjust the television set to room lighting or room lighting
to the set? Adapt the set's
brightness and contrast to room lighting -- not room lighting to the set
-- after the room lights have been turned on. Is
it alright to wear sunglasses while watching television? Generally, no. Sunglasses may shut
out too much light for good vision. If worn when not needed, they tend
to make it difficult for the viewer to adapt promptly to normal light
levels. If you are bothered by brightness, consult with an eye care
practitioner about the possible need for lenses more appropriate to TV
viewing. Possible
difficulties with TV viewing Children sometimes sit close to the
set. Does this hurt their eyes? While close-up viewing is certainly not
recommended, it is generally not harmful. It is best to watch television
from a distance of at least five times the width of the picture. Picture
details will appear sharper and better defined and the television lines
and defects will be less apparent. If your child persists in watching
television from a short distance, have his or her vision checked.
Nearsighted (myopic) children like to sit close to the screen. What
does it mean if the eyes water or if there is other visual discomfort
while watching television? It could indicate a problem that
needs professional attention. Some viewers, especially those over 50
years old, may find relief with special glasses for television viewing.
Discomfort could also indicate that the drainage passages which drain
tears from the eyes into the nose are partially blocked and require
examination. What
about color television for viewers with color vision deficiencies? Color deficiency (i.e. color
blindness) is generally not a barrier to enjoying color television.
However, viewers with color deficiencies may disagree with others as to
the "proper" color adjustment. A color TV picture properly
adjusted for most people may appear too green to a protanomalous (weak
red) observer, or too red to a deuteranomalous (weak green) viewer. When
the set is adjusted to "correct" its color, the resulting
picture is usually unsatisfactorily tinted for other viewers. Viewers
who are severely color deficient, the so-called "red blind" or
"green blind," will see little or no difference in widely
different color mixtures, and will not be bothered by most color
adjustments. TV viewing tips:
Good vision is vital to reading well.
And although vision may not be the only cause of reading difficulties,
it is one that is sometimes overlooked. Vision
skills needed to read Reading requires the integration of
eight different vision skills. Only one is checked by the typical school
eye chart test. Quick eye examinations may cover only one or two. Since
a comprehensive eye examination will cover the eight vision skills, it
is a must for anyone having trouble reading. The eight skills
include: Visual
acuity, or the ability to see
objects clearly at a distance. Visual acuity is sometimes measured in a
school vision screening. Normal visual acuity is referred to as 20/20
vision (or 6/6 vision in the metric system) -- a measure of what can
normally be seen at a distance of 20 feet, or six meters. If a problem
is discovered in the screening, a thorough optometric examination should
follow. Visual
fixation, or the ability to
aim the eyes accurately. One type of fixation, called direct, has to do
with the ability to focus on a stationary object or to read a line of
print. The other type, called pursuit fixation, is the ability to follow
a moving object with the eyes. Accommodation, or the ability to
adjust the focus of the eyes as the distance between the individual and
the object changes. Children frequently use this skill in the classroom
as they shift focus between books and blackboards. Binocular
fusion, or the brain's ability to gather information received
from each eye separately and form a single, unified image. Eyes must be
precisely aligned or double vision (diplopia) may result. If it does,
the brain often subconsciously suppresses or inhibits the vision in one
eye to avoid confusion. That eye may then develop poorer visual acuity (amblyopia
or lazy eye). Stereopsis, a function of proper binocular fusion enhancing the
perception of depth, or the relative distances of objects from the
observer. Convergence, or the ability to turn the two eyes toward each other to
look at a close object. Any close work, such as deskwork, requires this
vision skill. If convergence is poor then reading becomes uncomfortable
after a relatively short period of time and double vision may result. Field of
vision, or the area over which vision is possible. It is
important to be aware of objects on the periphery (left and right sides
and up and down) as well as in the center of the field of vision. Perception, the total process of receiving and recognizing visual
stimuli. Form perception is the ability to organize and recognize visual
images as specific shapes. A reader remembers the shapes of words, which
are defined and recalled as reading skills are developed. Treating
reading-related vision problems When a vision problem is diagnosed,
the practitioner will prescribe glasses or contact lenses, vision
therapy or both. Vision therapy involves an individualized program of
training procedures designed to help develop or sharpen vision skills
and possibly develop the eye muscles involved in focusing. Because reading problems usually have multiple causes, treatment must often be multidisciplinary. Educators, psychologists, optometrists and other professionals often must work together to meet each person's needs. The optometrist's role is to help overcome any vision problems interfering with the ability to read. This may require the use of corrective spectacles and/or the implementation of a variety of eye exercises. Once any vision problems are addressed, the student is better prepared to respond to special reading education efforts. |
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300A
Faunce Corner Road, Suite 101, North Dartmouth, MA 02747 © 2006 Southcoast Eye Care, Inc. ~ Last Updated: August 8, 2008 |
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