COLORBLINDNESS

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MargotSweeney

KellyBrustman

Adriana Dziedzic

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Retina: “thin, fragile membrane that contains millions of photoreceptor cells. It converts light energy into an electrical signal, which is transmitted to the brain via the optic nerve.”

THE EYE

Eye Doctors

• An optometrist is a health care professional who is licensed to provide primary eye care services and prescribes glasses. An ophthalmologist is a physician who specializes in the medical and surgical care of the eyes and visual system and in the prevention of eye disease and injury. They provide a full spectrum of care including routine eye exams, diagnosis and medical treatment of eye disorders and diseases and much more.

What is the name of the disorder? Other names?

• Color Blindness– “an inability to distinguish certain colors resulting

from an inherited defect in the light receptor cells in the retina of the eye.”

• Other common names for the disorder include: color deficiency or blindness-color

• More of a defect than a disease

How is the disorder inherited?

• Colorblindness is inherited as a recessive sex-linked disorder. Moreover, meaning it is inherited on the X chromosome and you must have a homozygous (two of the same) recessive allele in order to have the disorder. An interesting fact is that colorblindness affects mostly males due to the fact that they have one X chromosome and the Y chromosome doesn’t have any genetic information; henceforth having a 50% chance of having the disorder versus a female who has a 25% chance of having it because they have two different X chromosomes that both carry genetic information.

Can someone be a carrier for the disorder?

The definition of a carrier is a female who possesses one recessive or dominant allele depending if the disorder is autosomal dominant or recessive yet the other allele is normal thus the person doesn’t display the effects of the disorder. In terms of colorblindness, a person can be a carrier. For example, if there are two parents who have the genotypes XrXR and XrXR—look at the following offspring as a result of this crossing:

Xr XR

Xr

XR

XXrr XXRr

XXRr XXRR

What is the frequency of the disorder?

• Deficiency of green photoreceptor cells is more common than in red photoreceptors

• Females : less than 1% of the population - 1 in 200

• Males : 8% of the population - 1 in 20

What are symptoms/effects and prognosis of someone with this disorder?

• Inability to distinguish between certain colors• Duration : lifetime• Cause : genetic defect resulting in photoreceptor deficiency• results in inability to distinguish between certain colors• Someone who is colorblind must find ways to counter the effects

of their condition• Can obtain drivers license but will see the traffic light differently

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How is the disorder diagnosed?

• Ishihara Color Test : – Named after a Japanese optomologist– Test consist of a mosaic of colored dots containing

a number made up of different color dots

http://www.designrific.com/blog/2007/02/how-i-color-blind-person-see-world.html

Normal vision can see the number{7}

Colorblind vision would see this. The difference between the two are different kinds of color blindness.

Diagnosis cont.• Nagel Anomaloscope :– More precise– “Two colored light sources whose brightness can

be adjusted. The patient tries to match a given color superimposing the two light beams while varying their intensities”

http://www.colourmed.com/images/3.3lrg.jpg

*Try this out:http://www.colblindor.com/rgb-anomaloscope-color-blindness-test/

• there is no treatment or cure

Normal color vision

Red-Blind/Protanopia Blue-Blind/Tritanopia

Red-Weak/Protanomaly

Green-Weak/Deuteranomaly

Blue-Weak/Trichromasy

Monochromacy/Achromatopsia

Blue Cone Monochromacy

If you were Colorblind

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Works Cited“Color Vision Deficiency.” American Optometric Association. <www.

aoa.org>.

“Color Blindness.” Encyclopedia of Family HealthVol 3. 2005. Print.

“Color Blindness.” Magill’s Medical Guide Vol I. 2008. Print.

Rogers, Charles W. “Color Blindness.” Encyclopedia of Genetics Vol I.2004.

“What is colorblindness and the different types.” Color Vision Testing. <www.colorvisiontesting.com>.