PPRuNe Forums - Colour Blindness (merged)

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2close,
If you've already passed the holmes-wright (twice) then theres a good chance you'll be ok this time, also the beynes lantern is known to be easier then it so it all points to you being ok. Theres only one way to find out ;)

2C,

IF you passed the test then and especially if it was done for a CAA PPL can you not get written confirmation of this and be done with it?

FD

Cheers guys,

You would think that I would sail through it on the third attempt but I just can't help but worry over some of the 'horror' stories that I've read about LGW and the way the tests have been allegedly conducted at times.

I have the original test results from 1992 and now recent written confirmation from the eye specialist who conducted the test. I suppose what I have to do now is get that letter in the post to the CAA and see what they say. If they say I've got to do it again for the Cl.1 then c'est la vie. I book it, get down and do it, and if something goes pear-shaped....well, I'll cross that bridge if we get to it.

What's really infuriating is that all I want to get into is instructing, 99+% of which would probably be spent in daytime VFR conditions. Yes, I know there are many raised eyebrows and cries of,'The man has obviously lost his marbles', but there you go.

Hell, I'm fretting more over this than getting married. Irrational, or what?

FD - How do you manage with your FAA medicals if an examinee fails the Ishihara?

Best Regards,

2close

For the FAA it is pretty simple.

Do Ishihara test. If fail you can issue a medical for any class but with the restriction that goes with that (not for flight at night or by control of lightsignals)

If candidate wants to have the restriction lifted they have to write to the FAA in Oklahoma who will organise for the candidate to have a light signal test done at an FAA tower. If you pass that you get the restriction lifted. If you fail the test (which is done at dusk) you can then do a test a bit later in the dark, if you pass that you can fly by night but not for control by lightsignals.

For the FAA a pass for the Lantern test is also acceptable to have an unrestricted medical issued.

The FAA say they have no accidents on their database which are attributable to people's lack of colourperception.

Interestingly enough there is no requirement for colourvision for the NPPL (as far as I know)

HTH

FD

Hey guys,
I've talked to the CAA now so have abit more information. You CAN transfer a medical without a licence, it is to do with the JAA mutual recognition, however alot of other states do not see it this way, the UK seems to be the only one obeying the rules (good for them ;))

I have to now get the German AMC where I did my medical to fill in the medical transfer form and then send this off to the CAA with a copy of my german medical certificate and a fee of £22 and all should be well.

Hopefull it won't be TOO hard to get the germans to fill it in :=

Excellent news at long last.

Passed the Farnsworth Color Vision Perception Lantern Test today. Absoutely no problems - flew through it.

Funny thing was I also did better under proper conditions with the Ishihara and the City Unversity Tests than I've ever done before.

Just got to get the results off to the FAA now to get the restriction lifted.

2close

Does anyone know what's involved in taking the Beyne's lantern colour vision test? Apparently it's on offer for those who fail the Ishihara plates, as an alternative to the Holmes-Wright lantern.

hello,i'll be going for a medical check up soon because i applied to be a cadet pilot in AirAsia, but i'm worried about my eyesight.

a few months back,i had a eye check up and according to the doctor,i'm not as sensitive to color as others,but not colour blind.I noticed that when i look at the ishihara plates, i can make the number out if i look properly,i wanted to know if there are others like me

besides that,i noticed that i can actually memorise the numbers on the plate.i know it's not wise,but i really want to be a pilot.

Is perfect color vision a must?i never had problems differenciating colors my entire life(18 years of it)

hope some u u guys can give me some advice.

Colour Vision Deficiency (CVD) is more common than you may think. I've only just found out that my maternal grandfather had near monochromatic vision - luckily, it didn't pass down the line. However, I do have a slight CVD but like you it does not affect day to day life in any way, shape or form but I did have to jump through the hoops to get unrestricted JAA and FAA medicals - and only for private flying.

I wouldn't rely on learning the plates as the testing optometrist can select them in any order and from any of the books, I believe there are 12, 24 and 36 page versions of Ishihara. You may get caught out and in any case it's hardly in the spirit of safe flying (as you pointed out yourself).

Pefect colour vision is not an absolute necessity but SAFE colour vision is. Assuming that the medical standards and tests are the same in your country, if you make mistakes on the Ishihara Plates you will be invited to try a Colour Vision Perception Lantern Test, which will identify whether or not you can correctly and safely identify those colours that are used in aviation. If you identify them correctly, you are deemed colour safe and will have an unrestricted medical certificate, however, if you do not identify them correctly you will not be regarded as colour safe and, in JAA countries, you will not get a Class 1 medical and therefore cannot work commercially. What is absolutely essential is that the Colour Vision tests are carried out in the right lighting conditions - you would be surprised at the effect the wrong type and temperature of lighting can have.

There are different rules in different countries, however, and if you intend to fly commercially in any of these, it's best to check with the relevant authorities.

I hope your medical goes OK and you can follow your ambitions. Let us know the results.

This is interesting for the future.

Gene Research Sheds Light on Cure for Colorblindness

Colorblindness can likely be cured by gene therapy, according to Medical College of Wisconsin researchers who are conducting a treatment trial designed to discover what happens when a specialized set of normal genes is injected directly into the eye.

"I'm sure that, ultimately, gene therapy will cure colorblindness," said Jay Neitz, PhD, Medical College of Wisconsin Professor of Cellular Biology, Neurobiology and Anatomy. "It's not a matter of whether it will or not, it's a matter of when. I think the probability is extremely high."

Usually a hereditary condition that is present at birth, colorblindness afflicts more than nine million people in the US. Normal eyes distinguish color through three different photoreceptors located in the retina, some for red, some for blue and some for green. When one set of these many photoreceptors is missing due to genetic mutation, color-vision deficiency occurs to varying degrees depending on the severity of the mutation and which color receptors have been lost.

Dr. Neitz is collaborating on the gene treatment trial with his wife, Maureen Neitz, PhD, who is on the Eye Institute staff and a Medical College Professor of Ophthalmology, and Eye Institute surgeon Thomas B. Connor, MD, Medical College Associate Professor of Ophthalmology. (Quotes in this article are from Dr. Jay Neitz.)

The project is focused on the cone-shaped photoreceptors in the eye, which are responsible for defining color and visual acuity in normal light. The eye employs other photoreceptors, shaped like rods, for vision in dim light.

"If something happens with one of the cone photoreceptors, you have colorblindness," said Dr. Neitz. "If something happens with two out of the three, if they're the red and green ones - the blue cones are so rare - you end up with a blinding condition. So the blue cones are just as important for color vision but they're not very important for the rest of our vision. You can lose your green cones, too, and maybe those would influence your vision. That person's vision may not be 100% normal, but pretty close."

Same Genes Affect AMD
The research into gene therapy for colorblindness may also have applications in diagnosing and treating age-related macular degeneration (AMD), the leading cause of blindness in older populations in the US, because the same cells are involved. In colorblindness, genetic mutation kills off certain photoreceptors at a very young age in the life of those cells. Photoreceptor cells are killed much later on in AMD, but it is believed that they're also doomed by genetic factors.

"The same cells that create color vision are the ones that give us vision, said Dr. Neitz. "It's not like they're different. The very same cells that are affected in colorblindness are the ones that are affected in age-related macular degeneration. If certain kinds of things go wrong it gives you colorblindness. Other things go wrong, and you get age-related macular degeneration. In both cases, it's the loss of function in those cones that give you a loss of vision."

Images in Dr. Neitz' office, looking very much like photographs of stars in the universe, show the array of photoreceptors in the retina. Bright areas are living photoreceptors while missing photoreceptors are represented by dark "holes".

"Age-related macular degeneration also has a very large component, we believe, where the same gene that causes that (colorblind) person to lose his cones at a certain age is the same gene that cause people to lose their cones when they're 65 years old," said Dr. Neitz. "In other words, that person had a set of green cones at one time. If he hadn't had them, there would be no holes left behind.

"We believe that there is a gene mutation that caused that cell to die. So it's originally born and it lasts for some period of time. There are different kinds of mutations. Some of them are more deadly than others. That particular mutation is a very, very deadly one. Once you have it, the life span of the cone might be only two or three years. There are other mutations that are only mildly toxic, so you can go through life and your vision lasted for fifty, sixty or seventy years. Ultimately, the cone will die just as those cones did (in the colorblind person whose cones died very young)."

Putting Normal Genes Into the Eye
In the colorblindness trial, normal genes are being injected directly into the retinas of animals to take the place of the missing genes and, it is hoped, confer normal color vision.

"Just as there are three different kinds of cone photoreceptors in the eye - red, green and blue - each one of those is encoded by a different gene," said Dr. Neitz. "There's a red photo-pigment gene, a green one, and a blue one. Those are then expressed in those different cones to give you the red, green and blue cones.

"In general, we can take a blood sample from someone, and since every one of your cells contain all of your DNA, we can look at the cone photo-pigment genes and see if there are mutations. In the case of colorblindness, we have been able to identify the kinds of mutations in the cone photo-pigment genes that underlie colorblindness. Basically, we have outlined the genetic basis for colorblindness."

"For our particular gene we have already piloted the whole retrovirus that we're using and already put it into rat eyes," said Dr. Neitz. "We know that it will attack the photoreceptors and turn on inside the photoreceptors. The question is, can we get it to work in this monkey model and if it does work, does it confer color vision?"

The researchers are using a retrovirus to take advantage of cellular mechanics in the same way genetic therapy is used for other diseases, Dr. Neitz said, adding that the eye has the advantage of being a closed vessel so gene therapy can be targeted very directly. Photoreceptors are located in the retina, the back layer of the eye. To introduce the normal genes, the retina is clinically detached very briefly from a nutritive eye layer directly in front of it, creating a space in which a fluid can bathe all of the photoreceptors before the layers come back together.

Retrovirus "One-Ups" Virus
"What's in this fluid is the missing gene," said Dr. Neitz. "The problem is to get it into the genome so that it can be expressed. To do that, the gene is being carried by a retrovirus. Normally, what a virus does is attach itself to a cell. Since it doesn't have any of the machinery for copying its DNA, it uses the cellular machinery. The virus injects its own DNA into the cell, and that 'hijacks' the cell's machinery in order to replicate the DNA.

"In gene therapy we do the opposite. We one-up the virus, hijacking the mechanism that attaches itself and injects its DNA. The normal DNA sequences that are responsible for replicating the virus have been removed, because once they get into the cell they will replicate over and over again and burst the cell.

"In its place we've put the DNA that makes the human cone photo-pigment. The virus now will attach to the cell, putting the human cone photo-pigment gene in there. By mechanisms that we don't really understand that gene will ultimately integrate into the genome and become functional."

Dr. Neitz noted that this is the first trial ever of gene therapy in any animal involving the cone photoreceptors as a target. "I feel really confident about this, and since all the pieces are in place I'm hoping that it will work in a monkey within two years, he said. "If it works in a monkey we have to go to human trials and have to get FDA approval and so forth, so it could be about five years to get to the point where we're able to use the technique in humans.

"If you're interested in people's vision, it's really cone vision that's important. In the long run we're hopeful that this kind of gene therapy will become a way to treat a wide variety of blinding disorders that affect the cone photoreceptors - they're really the big target in both colorblindness and in AMD."

Dan Ullrich
HealthLink Contributing Writer

Article Created: 2004-04-14
Article Updated: 2004-04-14

I'm suffering from the same problem and I'm trying to get the signallight test done in the USA. (I'm currently in the USA.)

It is quite hard for me to tell the difference between green and white, even if the JAA Medical Examiniers tell me all the time I'm "redblind".
But whenever I fly with a friend I have no problems at all seeing PAPI/VASI lights or see the rotating beacon from airports. Since we fly most of the time at night, I must say it is easier for me to see traffic, buildings, etc. at night than during the daytime. Every once in a while I see traffic and aiports even before my friend does...

On the Anomaloscope I was twice below 1.0, one time 0.5 and missed the European standart by 0.1 and the second time the examinier refused to tell me the AQ (the number). For my first medical that I passed under LBA rules, I was testet as a "greenblind".
Well also my last european medical Examinier told me I shouldn't even try to become a pilot, I'm a hopeless case, but I studied the JAA FCL 3 and read the the allowed AQ values are 0.6 to 1.4.

Now since I left more than $800.00 in Europe just to get my medical, I thought I may try it in the US and I got my first class medical with the regular restriction "Not valid for night flight and color signal control. None.".
Now I'm trying hard to take either the flight test or the signallight test in the US, but since I screwed up so many tests in Europe I'm afraid that my dream that I had for years will be completly destroyed.
Is there a chance to retake the test, in case you failed it?

Thanks in advance

Robert