Fred’s Head from APH, a Blindness Blog

Fred’s Head, offered by the American Printing House for the Blind, contains tips, techniques, tutorials, in-depth articles, and resources for and by blind or visually impaired people. Our blog is named after the legendary Fred Gissoni, renowned for answering a seemingly infinite variety of questions on every aspect of blindness.

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Friday, September 01, 2006

Are You Color Blind?

Color blindness is expressed as a person being unable to perceive the full spectrum of colors the way the average human can. Color blindness itself can be caused by just about any problem with a component of the visual system. I think most types are caused by a person's ganglion cells (the interface between the retina and the optic nerve) not being able to fully distinguish between two colors. Each ganglion cell is designed to be sensitive between two color poles, so if it can't tell one end of it's sensitivity spectrum from the other, a person looses the ability to distinguish that color. The afliction(?) isn't necessarily genetically based, as sometimes trauma can induce color blindness.

This test is designed to be a kind of 'anti color blindness test - i.e. it's one that color blind people will be able to pass, while normal vision will fail.

Click this link to take the test at the Structure & Strangeness website.

Click this link for the Ishihara Test for Color Blindness.

Color Blind Homepage

Are you color blind? Have you ever wondered why color blindness occurs? Do you think you are color blind, but aren't sure? Well, this site has answers and explanations that will answer all these questions.

What is Color blindness? This section covers what color blindness is and describes the different types. There are four different kinds and they are explained in detail with a color chart for each.

Why Are You Color blind? This section discusses the science behind it. Why exactly are people color blind? It also goes into detail here why more men are color blind than women.

The next four sections all deal with helping you diagnose children with color blindness and if they are color blind, how you can tell, what you should do and how to effectively teach them.

Do you want to test your vision? Well, you can test for color blindness at the site with the "I Want to Test my Color Vision" section. You go through several different flashcard type exercises where you should see something if you aren't color blind.

Click this link to learn more about color blindness:

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