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Answers to Common Questions about Color Blindness
Q. What is color blindness?
A. Color blindness is the
common name for color deficiency. Color deficiency is the
condition in which the number of colors and shades seen by an
individual is less than normal. There are various degrees of
color deficiency, ranging from mild difficulty in recognizing a
few colors to an inability to recognize any colors.
Q. How does a normal person (trichromat) see color?
A. There are three visual color
pigments in the cones of the retina, which are sensitive to
red, green and blue. Each cone has a separate sensor so that
different cones are stimulated by different wavelengths of light
(colors). The cones react to the primary colors: red, green, and
blue, and send messages to the brain which mixes them in appropriate
proportions to provide normal color vision.
Q. Can a trichromat have a color deficiency?
A. Yes. In fact, most who are
red-green color deficient are trichromats who have a weak reception
for one of these colors, mainly green. Therefore, more than a normal
amount of green in addition to red and blue is required by these
individuals to produce all of the colors known to them.
Q. What are the most common color deficiencies?
A. Red and green. In each of
these cases, the person also finds other colors difficult to
distinguish.
Q. How does one know if he or she is color deficient?
A. By recognizing some of the
symptoms of color deficiency or taking a color- deficiency test.
Color deficiency is not obvious. In fact, Dalton, who first
described color blindness, did not recognize his own color defect
until age 26.
Q. What are some symptoms of color deficiency?
A.
Color deficiency is suggested if a person’s choice of color in
ordinary life is often questioned by other people. Another symptom
of color deficiency is a person’s preference for blues and yellows
as against reds or greens. Further suggestion of color deficiency is
a person’s difficulty in seeing veins or freckles. A color-deficient
person is normally insensitive to fall foliage. Some color-deficient
persons cannot distinguish black coffee from coffee with cream.
Many have difficulty in recognizing the colored signals used
in marine navigation, or on the highway. Also, the color of painted
surfaces is easier to see than that of colored fabrics. School
children may experience difficulty.
Q. Where can one be tested?
A. Eye practitioners are equipped
to test the whole family for color deficiency.
Q. Are many people color deficient?
A.
Yes. In the United States alone, there are approximately 10,000,000
males and 600,000 females who are color deficient. Most of these
persons may suspect but do not really know they are color deficient.
For a variety of reasons, they do not tell their friends or
families.
Q. Why is a person color deficient?
A.
The most accepted theory is that missing or defective nerve fibers
in the cones of the retina cause color defects. However, the
mechanism is not completely understood.
Q. Is color deficiency a disease?
A. Not necessarily. It is an
inherited, sex-linked characteristic. The female is the carrier. The
female offspring of a color-deficient father will most likely
transfer this genetic abnormality to half her sons. Some retinal
injuries or diseases can also cause color deficiency.
Q. What is color laziness?
A. A condition which some
color-deficient persons appear to have; namely, a lack of interest
in color.
Q. Does a color-deficient person have difficulty in seeing colored objects?
A. Yes. In many instances, he may
not see them at all; for example, strawberries in the field or ripe
apples on a tree. When
his color deficiency is aided, he is able to see such objects.
Q. What colors are confusing?
A. A color-deficient person may
find it difficult to distinguish between red and green; between red,
brown and gray; between green, brown and gray; between green, gray
and certain blues; between red and black; and between light blue and
purple. Also, he is often unable to distinguish between shades of
the same color. Thus, he may confuse a cool yellow with a warm
yellow. To a color-deficient person, pink can look insipid and even
gray. Further, he might see a dull yellow as orange or light green.
In many instances, the only colors that a color-deficient person
commonly recognizes are blue and yellow. Further, pastel
shades of all colors are difficult to distinguish.
Q. Are any occupations a challenge to the color-deficient?
A. Yes. Many occupations assume a
person’s ability to identify by color. This is true in the
electronics industry where color-coded components are a standard
aspect of assembly. Color identification is also required in the
field of cosmetics, medicine, printing, agriculture, chemical analysis,
textiles, plastics, photography, and art. In fact, there is
practically no profession or trade which does not inherently use
color as a means of identification.
Q. Is it safe for a color-deficient person to drive an automobile?
A. It is a belief of those who
have studied this problem that there is indeed some danger in having a colorblind
person driving a vehicle. In some countries it is difficult to
get a driver's license. There are also restrictions against
commercial driving by color blind persons in many areas of the
United States.
Q. Is it dangerous to be color-deficient?
A. Yes. In marine navigation,
aviation and railroading, color signals are a vital part of the
traffic-control system. A person who is color deficient has no way
to identify these colored signals; this makes it extremely dangerous
to permit him to navigate a boat or plane or locomotive. In view of
the great increase and complexity of colored signals and lights on
highways, it can be hazardous for a color-deficient person to drive
an automobile unless his color deficiency can be corrected.
Q. What about hunting?
A. Hunting is a sport in which
there are approximately 2,300 accidental shootings each year. In the
typical forest or underbrush, a color-deficient person could easily
mistake a fellow hunter for the animal or bird being hunted.
Q. Is there any way to help the color deficient?
A. Yes. The ZELTZER X-CHROM™ soft
lens can help most color-deficient people.
Answers to Common Questions about the ZELTZER X-CHROM™ Soft Contact Lens
Q. What is the ZELTZER X-CHROM™
soft lens?
Q. What does the lens do? A. It increases the number of shades that a color-deficient person can see. Once these new shades have been properly identified, the color-deficient person can learn to recognize colors that he never knew existed. With greater use, his sensitivity to color increases.
Q. What is the first impression with the lens? A. The color-deficient person first fitted with a lens sees color as more “vibrant” than ever before. Many new colors stand out. These sensations soon become normalized and the person becomes accustomed to his greatly enlarged color discrimination.
Q. Is the lens difficult to fit? A. No. It is fitted in the same manner as any other soft contact lens.
Q. Will the lens reduce vision? A. In some cases, it might slightly reduce visual acuity. In most cases, however, acuity remains unchanged. The lens should not be prescribed if visual acuity is less than 20/40.
Q. Does the lens interfere with binocular vision? A. With adaptation, there is no binocular interference.
Q. Is it possible to have a pair of spectacles in which you have one clear and one tinted red lens and would that be of any help to the color blind? A. No. It would cause annoying reflections and uncomfortable head motions. Also, intervening light that surrounds the filter would be distracting and the filter itself is cosmetically more objectionable. Light transmission control is more effective with a contact lens.
Q. When can the lens be worn? A. The lens can be worn during a person’s waking hours, including day or night. However, there are some people who cannot wear the lens during night or in poor illumination. In general, the lens can be worn at work, play or driving a motor vehicle. It is subject to other common restrictions of contact lens such as removal before going to sleep.
Q. Can a senior citizen wear the lens? A. Yes, providing a person can wear a contact lens and wishes to see a broader spectrum of color, age is not a factor.
Q. What if one wears contact lenses now? A. The lens will not interfere with the regular use of contact lenses. It replaces one of those lenses for part of the time.
Q. Is the lens important for children? A. Yes. Approximately at the age of 12, when a youngster can take care of his personal possessions and assume responsibility, he can wear the lens. By wearing the lens at this early age he will avoid many of the learning problems and traumas that color-deficient children encounter in their education. The youngest child fitted to date is six years old.
Q. What if one wears spectacles? A. Spectacles can be worn with the lens as long as the combination of the two give the proper vision. Occasionally, a person using the lens will give up spectacles completely for contact lenses.
Q. What if no eye correction is needed? A. An uncorrected lens can be used by a color-deficient person who needs no eye correction.
Q. Under what conditions should the lens not be prescribed? A. When it is contraindicated and or the patient has poor binocular vision or ocular pathology.
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