Author Archives: @colblindor

A few weeks ago I released the new RGB Anomaloscope. A slight adjustment was introduced since the first release and I also added a little survey to make it more accurate. Now I’m happy to announce the severity upgrade of the RGB Anomaloscope color blindness test.

The diagram is now split into several colored areas. As your personal matching line starts growing from the center it is possible to find the severity of your red-green color blindness. A very short line in the center means you are not colorblind, compared to a line stretching along the whole diagram which means you are suffering from a strong color blindness.

This update was based on more than 1’000 color blindness tests taken so far.I hope this helps you to find out more about your color vision.

I also checked the resulting matching points and found some interesting facts. The diagram to the side shows the colors which were matched with red.

The interesting fact is, that there are two main areas which can be identified. This points towards a possible differentiation of red- and green-blindness.

Before I release another upgrade including also the type of red-green color blindness I would like to gather some more test data. So stay tuned for a future release of the RGB Anomaloscope.

Can I Pass One Color Blindness Test and Fail at the Same Time Another One?

September 12, 2008

@colblindor

Tests 7 Comments

There are different tests available to check your color vision. Unfortunately they can’t be easily compared one to each other. This yields to the question, can you pass one sort of color blindness tests while failing on other ones?

Have you ever heard of somebody who can pass the D-15 test, but can’t pass an Ishihara plate test? I’ve been told I was colorblind (for 20 years) because I can’t see all the numbers in the bubbles. I finally asked my optometrist what type of colorblind I was (out of curiosity) and he gave me the D-15 test to find out. I passed it with flying colors—all in the correct order.

My optometrist has never seen somebody pass the D-15 and fail the Ishihara (he gave me that as well…). Any ideas?

A very important but in some way hidden message in this question is, that you have to go to your optometrist for a reliable check of your color vision. Online color blindness tests are a good start but not the right tool to get secure test results.

Types of color vision deficiency tests

The most common color blindness tests can be arranged into four main categories. In each of those categories are many different types of tests available, whereas the system of the test stays the same.

Anomaloscope: The most reliable test which can tell you more about the severity and type of your color blindness. My RGB Anomaloscope shows you someway how an anomaloscope works.
Pseudoisochromatic plates: This test category is the most famous one. Invented by Prof. Ishihara they are often called Ishihara plates tests. Based on the idea of colored dots different tests are used.
Arrangement tests: This tests are based on differently colored discs which have to be arranged in the correct order. They range from 15 discs (D-15) up to 100 discs.
Lantern tests: The most easiest test category developed over 100 years ago. They were originally used to check if you can work for a railway company and distinguish the different signal lights.

When you read through the list above you can easily guess that all those different color blindness tests can’t have the same sensitivity. Some are very sensitive like pseudoisochromatic plates. They are sometimes even not readable for people with normal color vision. On the other side the lantern tests are best to check if you are fit to do certain jobs and are not checking if you are only slightly colorblind.

Pseudoisochromatic plates, arrangement tests with 100 discs and anomaloscopes are the most sensitive and detailed color vision deficiency tests.
Looking at arrangement test you will have less sensitiveness with less discs. I don’t make that many mistakes on a D-15 test but I am very much red-blind.
Lantern tests are not good at testing the severity of your color blindness and are the least sensitive tests.

To conclude: you can easily fail an Ishihara plates tests and pass a D-15 arrangement test at the same time. I would say many people with a low to moderate color blindness will receive such a test result.

What I don’t understand is why your optometrist was astonished by your test results…

Interview with the Author of Colour Blindness: Causes and Effects

August 26, 2008

@colblindor

People 2 Comments

The book Colour Blindness: Causes and Effects is one of my favorite sources for all kind of information related to color vision deficiency. About one week ago I was contacted by the author of the book Donald McIntyre.

I invited him to join us for an interview and I am very pleased that he answered me back so quickly. Please read on and learn about Donald’s color vision deficiency—and more.

Colblindor: Are you suffering from any color vision deficiency yourself?
Donald McIntyre: Yes, I am a protanope. That is to say, I completely lack the set of cones in the retina that are sensitive to long wave (red) light. Reds appear very dark to me and I have great difficulty distinguishing among the range of reds, greens and browns (plus several other confusions).

Colblindor: What inspired you to write a book about color blindness?
Donald McIntyre: I have been aware of my colour vision deficiency since childhood. When I tried to find out more, all I could find were simple one page magazine articles, or highly academic research publications. There was a need for a book that explained colour vision deficiency to the ordinary reader, but in sufficient depth to answer the many questions that arise. Since the book didn’t exist, I decided to write it myself.

Colblindor: If you would write it again, which aspects would you highlight more deeply?
Donald McIntyre: It would have been nice to have time to find more anecdotes about the experiences of colour-blind people in different walks of life. Has any footballer ever passed the ball to the wrong side? I couldn’t find one to speak to.

Colblindor: Do you think there will be a treatment of color blindness in the near future?
Donald McIntyre: Unfortunately not. The computer-based simulations can give a very good idea to the colour normal of what we colour defectives see. But not the other way round!

Colblindor: What do you think about the fact that many colorblind people can’t become pilots, police officers or firefighters?
Donald McIntyre: The problems with colour vision deficiency become serious when a person has to make a critical decision on their own, especially where safety is involved. For instance, there are successful colour-blind electronic engineers who carry out development work in the lab. However, no colour-blind engineer should install or repair wiring in the field.
An important and often overlooked fact is that there are degrees of severity in colour vision deficiency. Protanopia (my sort) is the worst. At the other end of the range of severity, mild deuteranolamy involves a slight shift in the sensitivity of the middle wave cones and may not be a problem in many jobs. The commonly used Ishihara test is very sensitive and will pick up the mildest defect. If a person feels they have been unjustly barred from a profession, they can ask for a more detailed vision assessment and argue their case.

Colblindor: What would you tell a person who just found out that she is colorblind?
Donald McIntyre: First of all, it’s not that serious. Many people do not realise that they have one of the milder forms of colour vision deficiency until adulthood, perhaps when they are tested when applying or a job. It is worth finding out about colour-blindness at a young age, to avoid training for a profession that may produce problems later on. I would not go along with those who say the colour deficient view of the world is “equally valid”. We do lose out on some of the pleasure that colour can give, but there are plenty of other delights in the world.

Dear Donald, thank you very much for your time, for joining the interview and of course for your book.

New Release of the RGB Anomaloscope Color Blindness Test

August 23, 2008

@colblindor

Tests 2 Comments

I released the first version of the RGB Anomaloscope about a half a year ago. Since then more than 15’000 tests have been taken from many thousand colorblind and not colorblind people all around the world.

During this time I learned a lot more about this test and that’s why I updated it. So today I would like to announce the second release of the RGB anomaloscope color blindness test. It is still not like a real anomaloscope because of the three color limitation of computer displays (RGB). But I hope with this improvements we will get some better results and can give you a better prediction of the severity and type of your red-green color blindness.

The following attributes of the test have been adjusted:

The to be matched colors have all the same brightness now. This makes the result easier for comparison.
Instead of matching red or green to a yellow color, you have to match now some sort of yellow to different red-green mixtures. This gives a better readable test result.
To get a more precise test result, the selection of the last color matches is based on your ongoing test.
The test shows now a line instead of only circles. With this adjustment you can easier spot your personal result.

The most important adjustment is based on the equal brightness of the colors to be matched. This should make it easier to spot red-blind compared to green-blind people. If you have some sort of red-blindness, the green color shades look much brighter than red ones. And this is only true for red-weakness or red-blindness.

Enough of talking, just check out the new RGB Anomaloscope Color Blindness Test. Hope you like it.

The Most Frequently Asked Questions on Color Blindness

August 13, 2008

@colblindor

People 1 Comment

Since I started Colblindor more than two years ago I posted 233 articles, count as of today 623 comments and I was contacted more then 350 times—with increasing frequency. So I thought it is about time to write an FAQ on color blindness.

So far I put together the six top questions I get asked almost on a daily basis.

You can find the detailed answers at full length under the separate page Color Blindness — Most Frequently Asked Questions. In this short article I will only feed you with some very compact answers.

FAQ Color Vision Deficiency

Is there a cure for color blindness? — No. There are some scientists experimenting with color vision genes, but this won’t be available in the near future.
Can I correct my color blindness? — No. Neither glasses nor lenses or any other tools can correct it. But some of them may shift your spectrum of color sensation.
How can I pass the Ishihara test? — If you are colorblind, you can’t pass it. Some lenses might help you but are usually not allowed during testing.
Is my son colorblind? — Don’t be concerned. Wait until he goes to kindergarten and then ask yourself this question again.
Can women also suffer from color vision deficiency? — Yes. About 0.5% of all women are colorblind; 16 times less than men.
Which type of color blindness am I suffering from? — Only your eye specialist can tell you that. But some online color blindness tests might give you some clues.

If the answers were just to short, read them at full length. But if your question isn’t mentioned at all, don’t hesitate to contact me.

Color Blindness in Medical Jobs

July 9, 2008

@colblindor

Professions 20 Comments

Color vision deficiency is a very common disease—specially among men. So there have to be also many colorblind doctors and health professionals. Do you know if your medic is colorblind? And what if he really is, did he take some wrong decisions because of his color blindness?

Perfect or good color vision is not yet a precondition for any medical jobs. And there aren’t many studies about color vision deficiency and how it affects medical skills. J. Anthonny Spalding did a research on exactly this topic about ten years ago and brought together some interesting and still newsworthy results. He called his paper Colour vision deficiency in the medical profession.

Several studies in the last century have shown, that color vision deficiencies are occurring at about the same rate for doctors as for the population at large. In one of those studies, colorblind doctors were asked about their most common problems caused by their color vision deficiency:

body color changes of pallor, cyanosis, jaundice, and cherry red
rashes and erythema of skin
charts, slides, prints, and codes
test-strips for blood and urine
ophthalmoscopy
blood or bile in urine, faeces, sputum, or vomit
otoscopy

This is a quite impressive list of diseases which could be wrongly diagnosed or overseen by a colorblind doctor. If they know about their color vision deficiency—not every doctor knows about it—they try to overcome it by closer observation, asking others, and paying more attention to the patients medical history.

By taking greater care and the fact, that there are many diagnosis not involving colors, it is widely accepted that your colorblind doctor performs as well as a non-colorblind medic. There are also not really any serious errors known based on a misjudgment of a doctor suffering from a color vision deficiency.

But still, there are some situations where color blindness could be the cause for wrong decisions:

If a single sign of observation is essential to take the correct action.
Scanning of an area for the detection of small features (bacilli, rash,…).
Special work conditions like speed, alone, and poor illumination.

Dr Spalding concludes, that all this points to the need for screening for color vision deficiency for medical students and doctors. Which could specially be used for better counseling and an informed choice of career. But he also believes, that because of the wide range of specialties, the question of non-acceptance of applicants to medical school need hardly arise.

Probability of Color Blindness

April 15, 2008

@colblindor

People No Comments

It is well known, that approximately every twelfth man and every 200st woman suffers from some form of color blindness. But what about some real life probability numbers concerning color vision deficiency?

What’s the Chance of Color Blindness?

If you are a teacher you might ask yourself:
What is the probability that one of my pupils is colorblind?

And what about the chance to have a color vision deficient pupil
if you have only boys in your class?

Your son is maybe colorblind and joining the kindergarten pretty soon.
How big is the chance, that there is another colorblind child in his class?

…and he might also play in a soccer team.
Will he be the only colorblind boy in the team?

Are you a football coach? What is the probability that
one of your players from a team of 33 has a color vision deficiency?

Or you are leading at work a team of eight persons.
What’s the chance, that you have a colorblind person in your team?

Let’s say you know 100 persons. The probability that one of them
is colorblind has to be pretty high. But how high is it really?

In general, if two people meet, how big is the chance
that they are both suffering from color vision deficiency?

Before I will reveal the answers to the questions above or before you can compute it yourself, you need some more input. To calculate probabilities certain assumptions—like a base probability of color blindness or a class size—have to be taken. The results below are therefore based on the following numbers:

Probability of color blindness in men: 8%
Probability of color blindness in women: 0.5%
Average class size: 20 pupils
Group line-up: 50% male – 50% female

Based on this assumptions I calculated the following probabilities of color vision deficiency. Hover over the letters to see the results. But before viewing them, why don’t you try to answer the questions yourself? Just take a guess and have a look how close you can get to the real probabilities of color blindness.

58% 81% 54% 57% 94% 29% 98.7% 0.18%

And in other words:

Almost every teacher or trainer has a colorblind pupil or team member.
If you are colorblind pupil, there is a big chance that there is another colorblind child in your class.
You can almost be sure that you have at least one colorblind friend.
Approximately every 500st handshake is between two colorblind persons.

If you have any further questions, don’t hesitate to contact me or just write a comment on this article.

Improving Color Vision with Lenses for the Colorblind

March 29, 2008

@colblindor

Tools 120 Comments

Every person suffering from color vision deficiency has the same dream: I would like to see the world as everyone else can and I would like to be able to name colors correctly. Color correcting lenses claim to make this dream come true.

The History of Correcting Color Vision

It is said that already in 1837 a German scientist called Seebeck was writing about the possibility to correct color vision deficiency with some sort of lenses. But only in the twentieth century many people investigated and developed different types of tinted lenses and glasses which should help colorblind people to improve their vision.

Many people thought that you really can correct a color vision deficiency and turn it into normal vision. As of today it is well known, that color blindness is in most cases a genetic defect which can’t be corrected except with not yet existent genetic manipulation.

The System of Lenses Enhancing Color Perception

How does it work? It is actually very simple. You just use a tinted lens in one of your eyes, usually in your non dominant eye, and that’s it. In this case both eyes actually see different colors and because of that the brain can extract some other information out of certain colors. You can also use two different tints in each of your eyes. This depends very much on ones personal impression. But it definitely won’t work if you use the same colored lenses in both eyes.

This works for all types of color blindness (protanopia, deuteranopia, tritanopia) in the whole range of severities, with one exception. If you suffer from a complete color blindness (achromatopsia) there is currently no system which can give you back color vision.

The Things You Should Know about Improving Color Vision

First of all you can’t really improve color vision, you can only let’s say adjust your color sensation. The manufacturers claim that you can pass Ishihara plates tests without any errors when using such lenses. And that might be true. But this doesn’t mean that your overall color perception is enhanced. You will also loose some of your color perception in another area of the color spectrum.

Facts You
Should Know

Here are some of the main handicaps when you are using tinted lenses to improve your color vision:

The performance on Ishihara plate tests improves a lot. But in contrary there is no significant improvement in lantern tests and in color arrangement tests.
Color perception improves in your problem area like red-green but at the expense of an increase in blue-yellow confusion.
Most people experience difficulties in dim light or at night when wearing color correcting lenses.
You might experience some distracting effects like lustre, fluorescence, 3-dimensional effects, judgment of distance and motion.

But most important: Don’t wear them for driving! If you come into dim light situations like a tunnel you might have some problems with judgment of distance or motion which isn’t safe for driving.

The Results of a Scientific Study about Color Correcting Lenses

In 2000 a group of four scientists of the University of New South Wales, Sydney, tested the ChromaGen contact lens system trying to find out if they can enhance color perception for colorblind people. Fourteen persons suffering from red-green color blindness were involved to test the efficacy in standard color blindness tests, and to evaluate subjective performance in the “real world” over a 2-week lens-wearing period.

Lens tints are available in seven hues (magenta, pink, violet, yellow, aqua, orange and green), and most tints are available at light, medium and dark densities. Most often the pink lens in its darkest density was felt to enhance color perception at the most. Second ranked was the magenta lens, also in the darkest density.

I already included some of the results of this study in the sections above. To me there are two more results which I would like to pass on to you. This might give you a better feeling, if such color enhancing lenses are something for you or not.

A. Would you
pay the price?

At the end of the two week lens-wearing period the people joining the test were asked whether they would be prepared to pay full cost of the lens, which is around $500 per lens. Only two out of 13 would be willing to meet this cost. One of them was really enthusiastic about them and the other one could use them very well on his job as a casino employee.

B. Would you
wear the lens?

One of the persons even returned the lenses, it was too much bother for him. The others expressed interest in wearing them on an occasional basis, maybe once or twice a week. For some of persons the disadvantages of lens wear just outweighed the benefits of them.

The Vendors of Color Correction Lenses

I suppose there are many different vendors all around the world. The following three are the most established ones:

ColorMax from Dr. Thomas Azman who developed the ColorCorrection System, a unique system of tests and filters for a systematic approach to color vision correction. (Based in Maryland, USA)
ColorView spectacle lenses help people with congenital red-green color deficiency to distinguish colors easier and reduce color confusion. (California, USA)
ChromaGen is a unique product that was developed to help patients who suffer from color deficiency. This product was used in the scientific study cited above. (United Kingdom)
Colorlite is also a leader in color vision diagnostic and correction. (Hungary)

Some products are available at certain optometrists all around the world.

Unfortunately I think that the dream of seeing colors as a colorblind person doesn’t come true. At least not with products like lenses which enhance color vision. They can get you a better color perception but I think the handicaps outweighed the benefits.

The New York Times also wrote an article about lenses which can enhance color vision at A New Technology That Colors the World (Sort of).

RGB Anomaloscope Color Blindness Test

March 11, 2008

@colblindor

Tests 14 Comments

The anomaloscope is the most accurate tool to classify your color blindness. Since it was developed by a German ophthalmologist just over 100 years ago it is used all over the world to check the severity of ones color vision deficiency and its specific subtype.

The classical anomaloscope is used to identify red-green color blindness. It consists of two different light sources which have to be matched. One source is a yellow lamp which can be adjusted in its brightness. The other one is made by a mixture of a red and a green lamp, whereas the mixture between those two colors can be calibrated.

According to the match the tool can tell you details about the following facts of your color blindness:

Red- vs. green-blindness,
dichromacy vs. anomalous trichromacy,
and the severity of your color vision deficiency,

As this tool is only available as a quite expensive equipment I tried to simulate it online. I knew that there is only a little chance to get the same results as the real anomaloscope. But I tried it anyway and designed the RGB Anomaloscope. As all computer displays are based on the colors red, green, and blue, it will always be a simple approximation of the real test.

The diagram below shows the test results as matching-lines of some red-green colorblind persons. Each point means that this person matched a certain red-green combination to some shade of yellow. Non-colorblind people would only match the point 50/50 with some variances.

Unfortunately the results didn’t turn out as I thought. I couldn’t find any split between red- and green-blind persons. Also it isn’t that easy to judge the severity of a red-green color blindness.

Anyway, the test is online and you are welcome to try it out. Maybe there will be some improvements in future releases of the RGB Anomaloscope Color Blindness Test, so stay tuned.

A big thanks to everybody who helped me to develop the test.

New Color Blindness Test – Looking for Red-Green Colorblind Test Persons

February 10, 2008

@colblindor

Tests 3 Comments

The anomaloscope is the most precise instrument when it comes to analyzing red-green color blindness. It was developed about 100 years ago and is still in use all over the world.

An anomaloscope is based on two different light sources which have to be brought to a match. You can match them by adjusting either the brightness of a certain yellow color or the proportion of mixture between a green and a red light. According to the matches you can make the eye specialist can give you detailed information about the severity and subtype of your red-green color blindness.

The RGB anomaloscope uses exactly the same approach but as an online tool. But because computer displays are solely build up from the three main colors red, green, and blue, the results can’t be just transformed to this online color blindness test. And that’s why I need you.

I’m looking for red-green colorblind persons who would like to help me to develop the RGB anomaloscope color blindness test. The test is now online available as RGB Anomaloscope Color Blindness Test.

What do you have to do? Simply use the anomaloscope, that’s all. If possible you can take the test under different light conditions and using different computers. This increases the chance to get an accurate color blindness test in the end. And—of course—you have to be red-green colorblind yourself.

RGB Anomaloscope Diagram — Color Blindness Test
Results Diagram

On the left side you can see my test results. Every dot represents a color match. As I’m strongly red-blind the matching area spans the whole possible spectrum.

If you would like to join and help me to develop this new online color blindness test just contact me. Please write me also about the subtype and severity of your red-green color blindness—as good as you know. You can check this at Which Type of Red-Green Color Blindness is It? After contacting me I will send you the link to the tool and the password to get in.

And please be aware we might not get the results which I would like to see. So maybe I can’t give you any better results than the ones you already have.