colour blindness drka

8/2/2019 Colour Blindness Drka

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COLOUR BLINDNESS

Skill labFakultas Kedokteran

Universitas Muhammadiyah Yogyakarta


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Color blindness or color visiondeficiency is the inability toperceive differences between some

of the colors that others can
http://en.wikipedia.org/wiki/Color_visionhttp://en.wikipedia.org/wiki/Color_vision


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normal


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protanope


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deuteranope


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tritanope


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Total colour-blindness


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retina

Normally, there are three kinds

ofcones (each one sensitive to aspecific range of wavelengths):

"red" cones (64%)

"green" cones (32%)"blue" cones (2%)

The normal human retina contains two kinds of light sensitivecells: the rod cel ls (active only in low l ight) and the conecel ls (active in normal dayl ight and responsible forcolor perception).

The different kinds of inherited color blindness result frompartial or complete loss of function of one or more of thedifferent cone systems.


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Blue conesabsent incentralfovea

Red, greenand blue conesensitivity vs.wavelength

curves


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CAUSES

GENETIC : sex-linked recessive / X-Linked

mutations from at least 19different chromosomes and 56different genes

Inherited color blindness congenital, non congenital (conedystrophy)

Others : trauma, radiation, maculardegeneration


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Females

X

N

X

N

=

Normal

XN

Xn

=

Carrier

Xn

Xn

=

affected

Males

XN

Y =

Normal

Xn

Y =

affected


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BUTA WARNA

BUTA WARNATOTAL

BUTA WARNAPARSIAL

Monochromacy

Rod monochromacy,

Cone monochromacy

Achromatopsia

Rod monochromacy,

Color Agnosia

cerebral Achromatopsi

Dichromacy

Protanopia

Deuteranopia

Tritanopia

Anomalous trichromacy

Protanomaly

Deuteranomaly

Tritanomaly


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EPIDEMIOLOGIColor Deficiency Males Females

Protanopia 1% 0.01%Deuteranopia 1% 0.01%

Protanomaly 1% 0.01%

Deuteranomaly 5% 0.4%Overall (red-

green)8% 0.5%

Tritanopia 0.008% 0.008%

Tritanomaly Rare Rare

Rod

monochromatism

Rare Rare


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Monochromacy

is the condition of possessing only a single channel forconveying information about color. Monochromatspossess a complete inability to distinguish any colorsand perceive only variations in brightness.

Rod monochromacy, frequently called achromatopsia,where the retina contains no cone cells, so that in additionto the absence of color discrimination, vision in lights ofnormal intensity is difficult.

Cone monochromacy is the condition ofhaving bothrods and cones, but only a single kind of cone. A conemonochromat can have good pattern vision at normaldaylight levels, but will not be able to distinguish

hues.


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protanopia, deuteranopia,protanomaly, and deuteranomaly

SEX-LINKED

have difficulty with discriminatingred and green hues.

Red-green colorblindness


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PROTANOPIA (dichromacy)

1% of males

(no red cones; only green andblue)

unable to distinguish between colorsin the green-yellow-red section of thespectrum

the brightness of red, orange, andyellow is much reduced compared tonormal.


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17

B RG

437 nm

533 nm

Protan Dichromat(no red cones; only green and blue)

1% ofMales


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18

B G

437 nm

533 nm

Protan Dichromat(no red cones; only green and blue)

1% of Males (there is no redcurve)


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Protanomaly

Protanomaly (1% of males, 0.01% offemales)

Having a mutated form of the long-wavelength (red) pigment

whose peak sensitivity is at a shorterwavelength than in the normal retina,

less sensitive to red light than normal.

reds to reduce in intensity to the pointwhere they can be mistaken for black. Both protanomaly and deuteranomaly

are carried on the X chromosome.


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20

B RG

437 nm

533 nm

Protanomalous(red shifted toward green)

1% ofMales


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Deuteranopia(dichromacy)

1% of males

no green cones; only red andblue

unable to distinguish between colorsin the green-yellow-red section of thespectrum.

The deuteranope suffers the samehue discrimination problems as theprotanope


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B RG

437 nm 564 nm

Deutan Dichromat(no green cones; only red and blue)

1% ofMales


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25

B R

437 nm 564 nm

Deutan Dichromat(no green cones; only red and blue)

1% of Males (there is nogreen curve)


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Deuteranomaly

most common - 6% of males, 0.4% of females Having a mutated form of the medium-wavelength

(green) pigment. The medium-wavelength pigment is shifted towards the red

end of the spectrum resulting in a reduction in sensitivity tothe green area of the spectrum.

Unlike protanomaly the intensity of colors is unchanged The deuteranomalous person is considered "green weak".

For example, in the evening, dark green cars appear to beblack to Deuteranomalous people.

Similar to the protanomates, deuteranomates are poor at

discriminating small differences in hues in the red,orange, yellow, green region of the spectrum. One very important difference between deuteranomalous

individuals and protanomalous individuals isdeuteranomalous individuals do nothave the loss of"brightness" problem.


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B RG

437 nm 564 nm

Deuteranomaly(green shifted toward red)

5% ofMales


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Blue-yellow colorblindness

Those with tritanopia and tritanomaly have difficultywith discriminating blue and yellow hues.

Color blindness involving the inactivation of the short-wavelength sensitive cone system (whose absorptionspectrum peaks in the bluish-violet) is called tritanopiaor, loosely, blue-yellow color blindness. The tritanopes

neutral point occurs near a yellowish 570 nm; green isperceived at shorter wavelengths and red at longerwavelengths.

Mutation of the short-wavelength sensitive cones is calledtritanomaly.

Tritanopia is equally distributed among males and females. Jeremy H. Nathans (with the

Howard Hughes Medical Institute) proved that the genecoding for the blue receptor lies on chromosome 7, which isshared equally by males and females.

Therefore it is not sex-linked. Blue color blindness is caused by a simple mutation in this

gene.[21]
http://en.wikipedia.org/wiki/Howard_Hughes_Medical_Institutehttp://en.wikipedia.org/wiki/Color_blindnesshttp://en.wikipedia.org/wiki/Color_blindnesshttp://en.wikipedia.org/wiki/Howard_Hughes_Medical_Institute


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The Series of PlatesDesign as aTest for Colour-Blindness

By

SHINOBU ISHIHARA M.D., Dr. Med. Sc.

Emeritus Professor of Ophtalmology, Tokyo University,

Member of the Japan Academy
http://en.wikipedia.org/wiki/Color_blindnesshttp://en.wikipedia.org/wiki/Color_blindnesshttp://en.wikipedia.org/wiki/Color_blindnesshttp://en.wikipedia.org/wiki/Color_blindnesshttp://en.wikipedia.org/wiki/Color_blindnesshttp://en.wikipedia.org/wiki/Color_blindnesshttp://en.wikipedia.org/wiki/Color_blindness

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