The American Journal of Medical Sciences and Pharmaceutical Research
39
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TYPE
Original Research
PAGE NO.
39-42
10.37547/tajmspr/Volume07Issue03-06
OPEN ACCESS
SUBMITED
03 January 2025
ACCEPTED
05 February 2025
PUBLISHED
11 March 2025
VOLUME
Vol.07 Issue03 2025
CITATION
Kakharova Dildora Maribjanovna. (2025). Color perception disorders. The
American Journal of Medical Sciences and Pharmaceutical Research, 39
–
42.
https://doi.org/10.37547/tajmspr/Volume07Issue03-06
COPYRIGHT
© 2025 Original content from this work may be used under the terms
of the creative commons attributes 4.0 License.
Color perception disorders
Kakharova Dildora Maribjanovna
Andijan State Medical Institute, Uzbekistan
Abstract:
Daltonism is a vision disorder in which the eye
is unable to perceive one or more primary colors. This
disorder is caused by a defect in the X chromosome.
However, this is not the only cause of the disease. Color
perception may be impaired due to eye or nervous
diseases, traumatic brain injury, severe flu, stroke, or
heart attack.
This pathology was named after the English chemist
John Dalton, who also suffered from this disease, like his
relatives, discovered and described the pathology in a
book.
Keywords:
Color perception disorders, color blindness,
pathology, treatment, features.
Introduction:
Color vision in humans is provided by
special light-sensitive receptors located in the retina
—
cones. Various pigments contained in the cones allow
detecting three color spectrums:
1)
red with a wavelength of 552-557 nanometers
2)
green with a wavelength of 530 nanometers
3)
blue with a wavelength of 426 nanometers.
The transmission of the gene for color blindness is linked
to the X chromosome and is almost always inherited
from a carrier mother to her son. In men, the defect in
the X chromosome is not compensated. Today, 2-8% of
men and only 0.4% of women suffer from color
blindness. Acquired color blindness can develop in an
eye if there is damage to the retina or optic nerve.
Before the disease develops, difficulties appear in
distinguishing yellow and blue colors.
Monochromacy is a change in color perception in which
a person sees the world only in one color. The disease is
classified as an acquired disorder.
Dichromacy is a change in color perception in which
there is a structural disorder of the eye.
Daltonism is a congenital (less commonly acquired)
disease that manifests in various defects in color
perception. This feature of vision appears not only in
humans but also in primates.
There are some theories of color vision, and one of them
is the trichromatic theory of vision. It was first proposed
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by Mikhail Vasilyevich Lomonosov in 1756 when he
wrote “On the Three Matters of the Eye’s Depth.” In
1802, Thomas Young suggested that the human eye
has three types of color receptors, each of which is
sensitive to red, green, and violet. Half a century later,
in 1853, the theory of T. Young was supplemented by
the German biologist and physicist Hermann
Helmholtz. He suggested that to obtain different
shades, three primary, pure colors are necessary: red,
green, and blue. As a result of their mixing,
intermediate colors are produced.
Another theory is the opponent-process theory. In
1870, the German physiologist Ewald Hering
interpreted the results of color mixing, concluding that
the visual system contains three substances, each of
which perceives the colors of its opponent pair: red
and green, blue and yellow, black and white.
Depending on the spectral composition of the
perceived light, either synthesis or decomposition of
these substances occurs, creating the sensation of
color.
There are also other theories of color vision. For
example, in 1975, the Soviet scientist Sergey
Dmitrievich Remenko proposed a nonlinear two-
component theory of vision, according to which the
human visual system contains only two types of light-
sensitive elements
—
uniform rods and cones, which
contain pigments highly sensitive to multiple regions of
the spectrum. This theory suggests the nonlinearity of
the processes of color signal formation. The nonlinear
theory of S.D. Remenko describes the mechanisms of
signal processing by receptors, maintaining white
balance, and models the overall function of the eye.
However, it did not gain widespread acceptance. There
are various opinions on this topic. It is also important
to note that the listed theories and hypotheses are not
agreed upon and often contradict each other.
Problems with color vision disorders were covered in
the works of the English physicist John Dalton.
According to statistics, the percentage of people with
normal color vision is 90-92%, while about 8-10% are
partially or completely “color blind.” In 1794, J.
Dalton first conducted research and described the
vision defect, which was named daltonism
—
complete
or partial color blindness. This disease is most often
diagnosed in men. Women, as a rule, only pass the
pathology on by inheritance.
Thus, it can be concluded that light-sensitive cones
responsible for color perception are located on the X
chromosome.
There is another alternative theory presented in the
book of the famous American neuroscientist Mark
Changizi “The Vision Revolution: What, How, and Why
We See the Way We Do.” In his work, he outlines the
essence of his proposed “skin hypothesis.” Mark
Changizi believes that human color vision evolved for
observing significant and minor changes in skin tone,
which are determined by two physiological indicators:
excess/lack of blood and excess/lack of oxygen in the
blood. When blood accumulates under the skin, as in a
bruise, a blue color appears; if there is a lack of blood, a
yellowish tint appears. With excessive oxygenation, the
skin turns red; with oxygen deficiency, it slightly turns
green. Each of these processes helps determine a
person’s ph
ysical and emotional state, which is
particularly important in sexual signaling and disease
recognition. The neuroscientist’s ideas allow several
conclusions to be drawn. Our skin, besides its
thermoregulatory,
water-repellent,
and
elastic
properties, has remarkable, almost magical, color
properties
—
it can become colorful.
To diagnose color perception disorders in medicine,
various methods are used. The most well-known and
popular diagnostic tool is the Ishihara test. It consists of
polychromatic plates displaying numbers or geometric
figures composed of dots of varying color and
brightness. Against the background of these dots,
different colors are used to highlight numbers or
shapes. A person with normal vision can easily
distinguish them from the rest. If there are color
perception disorders, the patient will not be able to see
the hidden figures. Using the Ishihara test, the type of
color blindness is determined based on the colors and
number of figures identified by the patient.
The images are placed one meter from the eyes at the
same level as the patient, in good even lighting. The
patient examines the image for 7
–
10 seconds and then
describes what they see. The plates include trick images,
which only colorblind individuals with a specific type of
color blindness can see. The doctor can determine
which pigment is missing in the retina using these
tables.
To identify those who may try to cheat the test for some
reason, special control images are created. These plates
display figures that are clearly and distinctly visible both
to people with normal vision and those with any form of
color blindness. A total of 48 plates are used. The first
27 are the main ones, while the remaining 21 are
additional, allowing for a more in-depth analysis of
vision disorders. They are mandatory for professional
examinations of drivers, train operators, and pilots.
Color blindness testing with Ishihara plates is used
worldwide and provides the most accurate results
regarding the type and severity of the disorder. The
control images refine the diagnosis.
Another diagnostic method for color blindness is the use
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The American Journal of Medical Sciences and Pharmaceutical Research
of the Ishihara plates. This method also consists of
cards. They help identify which specific color
perception is impaired. There are four sets of cards,
each revealing a pathology related to one of the
primary colors.
The cards in the first set are used to detect
impairments in the perception of red and its shades.
The second set identifies pathologies related to the
inability to perceive green shades, the third set is for
blue shades, and the fourth set contains black-and-
white text for familiarization purposes [11].
For diagnosing this condition, the Polychromatic
Rabkin plates are used. There are 27 pages with images
in the form of numbers or geometric shapes made up
of circles and dots of equal brightness against a
background of pale-colored circles.
A person with normal color vision (trichomats) can
identify the numbers in this form. A color-blind person,
with blindness to one or more colors, will not see the
numbers or shapes on the pages. The table helps
determine which color the vision cannot perceive.
Doctors also use the Ishihara test to assess background
perception disorders. In photographs with patches of
different colors, some of them, with a uniform shade,
form a number, letter, or shape. A person with color
blindness will not see the image.
The disease can be diagnosed in children from the age
of three. Before this age, children do not see many
colors due to physiological reasons. If this pathology is
present at birth, the child should be examined by an
ophthalmologist once they reach the age of three.
Color blindness that is inherited cannot be treated.
Special corrective lenses with a special coating exist
that enhance certain colors, but they distort
surrounding objects. Ophthalmologists recommend
tinted glasses, which help improve color perception in
dim lighting.
Types of Color Blindness
1)
Achromacy
–
the inability to distinguish colors:
in this case, a person perceives only shades of gray.
2)
Monochromacy
–
the inability to see the full
range of colors. Only one color and its spectrum of
shades are available.
3)
Dichromacy
–
two colors are available. It is
divided into: protanopia
–
the inability to see red;
deuteranopia
–
problems with perceiving green;
tritanopia
–
the inability to perceive blue-violet colors.
4)
Trichromacy
–
all three primary colors are
perceived well. It can be normal and abnormal.
The last type lies between normal trichromacy and
dichromacy. If in typical dichromacy there is no ability
to distinguish between two colors, then in anomalous
trichromacy, a person does not struggle with the colors
themselves but with their shades. Just like in
dichromacy, here we also distinguish prot-, deuter-, and
tritanomaly, in which the perception of the red, green,
and blue parts of the spectrum is weakened,
respectively.
Sometimes, when certain shades are not perceived,
there is a compensatory enhancement of the perception
of other colors, thereby balancing the existing
deficiency. For example, patients who cannot
distinguish red tones from green ones can perfectly
distinguish khaki shades in a quantity inaccessible to
healthy people.
Molecular Mechanisms
The light-sensitive pigment rhodopsin consists of the
protein opsin and the chromophore 11-cis-retinal.
Photoisomerization of retinal into the trans-form
activates the G-protein transducin, which binds to
phosphodiesterase, catalyzing the hydrolysis of cGMP.
This leads to the closure of cGMP-dependent sodium
channels. The potential difference across the
membrane increases, and hyperpolarization spreads to
the synaptic terminal, where a nerve impulse is
generated and transmitted to the brain.
The regeneration of the photoresponse is ensured by
the enzyme guanylate cyclase, which restores the initial
concentration of cGMP in the cell, leading to the
opening of ion channels and the restoration of the initial
potential.
The perception of all shades (trichromacy) is ensured by
three types of cones with different spectral sensitivity,
which is determined by the combination of retinal with
a specific type of opsin. Genetic disorders leading to the
absence of a specific type of cones (dichromacy,
monochromacy) cause color blindness
–
daltonism.
CONCLUSION
Thus, daltonism is inherited from the mother to the
sons. Girls rarely suffer from it, mainly if both parents
are affected by daltonism. Girls, being carriers of the
gene, only pass it on by inheritance. Only acquired
daltonism can be treated. Inherited daltonism cannot be
cured. Inherited daltonism remains with a person for
life.
Along with the inability to perceive colors, people often
experience decreased visual acuity. Methods for
correcting and treating daltonism are being developed,
but as of today, scientific advancements in this field are
still not large-scale enough.
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