Red Green Weakness

By | June 8, 2022

The terms red-green weakness, red-green visual impairment or red-green blindness are the technical terms for the most common color vision defects, which are colloquially known as color blindness. Contrary to popular belief, red-green-blind people are not necessarily incapable of recognizing these two colors; there may also be a lack of differentiation.

What is red-green weakness?

Red-green color deficiency is a retinal defect that affects around eight to nine percent of the male population and only around one percent of the female population. There is a defect in one, two or all of the eye’s receptors responsible for color transmission, which leads to general color blindness or the most common color blindness, red-green blindness. For hydrocephalus definition, please visit

The red-green color blindness, which is also called Daltonism after its discoverer John Dalton. Those affected therefore suffer from some limited color vision. They are not able to distinguish between the colors red and green, and problems can also arise when differentiating other color tones if green or red have been added to them.

The disease can occur in various forms and is usually not experienced as a hindrance by those affected. An existing red-green visual impairment is an obstacle, especially when choosing a career. Those affected are not allowed to practice some professions such as sailors, police officers, taxi drivers or pilots.

However, red-green color blindness can also be an advantage for those affected, who are more sensitive to gradations of brightness, which means they have generally better night vision, and can distinguish khaki tones and shapes and contours better than non-color-blind people. The military likes to work with color blind people to verify the effectiveness of camouflage suits.


The cause of red-green blindness is a genetic change in the cones of the retina. Errors in the transfer of hereditary information to the chromosomes result in incorrect combinations of genes, which lead to disruptions in cone function.

The exact processes that lead to a red-green weakness are very complicated and can be looked up in relevant medical encyclopedias. It is important to know that a red-green weakness is always congenital and that it is inherited in a recessive manner.

In addition to the disturbance of the cone function, scientists suspect a reduced number of cones on the retina with an increased number of rods. The rods of the retina are responsible for seeing light and dark, which would explain the increased ability to see at night compared to people with normal vision. So far, however, this thesis has not been proven.

Symptoms, Ailments & Signs

The main symptom in the presence of a red-green weakness is the reduced ability to see the corresponding colors. The ability to distinguish between the colors red and green is affected here. However, there are numerous gradations here. A red-green weakness is not necessarily a color blindness.

Rather, it can also lead to poorer differentiation between red and green. This can be done depending on the exact shade. It may be that certain nuances of red and green are indistinguishable for the person concerned, while other nuances are clearly different for him. The restriction in seeing red and green means that those affected perceive significantly fewer different color tones.

The more the perceived wavy lines overlap in the corresponding cones of the eyes, the more difficult it is for those affected to distinguish between red and green. The colors are referred to by most sufferers as shades of gray or brown. In any case, both eyes are affected and the disease is lifelong.

Due to the fact that most of those affected have not experienced correct color vision, there are hardly any restrictions. The rest of the eyesight is not restricted. Those affected by red-green weakness can also compensate for their limited color vision. This is achieved by classifying the perceived brown or gray tones or by simply knowing what color an object should be.

Diagnosis & History

Since the introduction of the euro in the European Union, self-testing for red-green color blindness has been possible without any problems, as physicists at the Universidad de Extremadura in Cáceres found out: If you cannot distinguish the color of the 5 and 20 cent coins, you are almost certain Probability red-green-blind.

Since those affected cannot distinguish between colors that have a high proportion of red or green, they are unable to objectively distinguish between these two coins.

Of course, ophthalmologists have more far-reaching diagnostic methods at their disposal to diagnose not only the red-green color weakness, but also its degree of severity. The most commonly used are the Ishihara color charts, the Farnsworth test and the spectral color mixer. The task on the spectral color mixer is to set a yellow circle based on color mixtures, whereby color vision defects quickly come to light.

This complex test is the typical professional aptitude test. Testing the ability to distinguish between colors is easier with the Ishihara color charts, on which numbers are shown in brightly colored blobs of color, and with the help of the Farnsworth test, which asks the test person to assign the color.


There are no real complications in the medical sense when red-green color deficiency is present. It is an actual condition in the eye that does not mean any organic impairment and also does not mean any increased risk of any diseases in the eye area.

Complications in the broadest sense only arise for those affected if their color blindness specifically limits them. This can be the case, for example, when choosing a career, where correct color vision is necessary, for example as a pilot or in the course of laboratory tests. Whether this significantly affects those affected is an individual question.

However, most of those affected can come to terms with their red-green weakness very well – if only because they don’t know any other way. When driving at night, however, a red-green weakness can mean an increased risk of accidents. After all, red traffic lights are very difficult to perceive in poor light for people with red-green color blindness.

Furthermore, very concrete problems occasionally arise in everyday life. For example, the colors red and green are often used to distinguish or mark elements (text, image, toy, etc.), signage and numerous everyday objects as well.

When should you go to the doctor?

People who notice an impairment of vision should always consult a doctor. The extent of the visual disturbance and the cause of the symptoms must be clarified. A diagnosis is required so that a suitable treatment plan can be developed. Blurred vision, problems recognizing moving objects or abnormal color perception should be discussed with a doctor.

If discrepancies in vision can be detected in a direct comparison to people in the immediate vicinity, the person concerned needs various tests to clarify the symptoms. A direct exchange with other people in everyday life helps to assess the existing problem. It should be used as a basis for describing any irregularities noticed by the doctor as precisely as possible.

If adults notice behavioral problems in their offspring or peculiarities in the color descriptions of objects, they should consult a pediatrician together with them. Naturally, the children cannot become active independently and must therefore be presented to a doctor. Since the red-green weakness can lead to significant problems, especially in road traffic, the person concerned is subject to an increased risk of accidents. If developments occur that substantiate the suspicion of a color perception disorder, a doctor should be consulted as soon as possible.

Many sufferers do not notice the disorder for a long time. As soon as there are indications and suspicions, a medical consultation is advisable.

Treatment & Therapy

Since those affected by red-green color blindness can master their lives very well and only rarely experience limitations in their everyday activities, no therapy is usually necessary. Therefore, no treatment options applicable to humans have been developed to date.

Another reason for the lack of therapy options is the scientific interest in color blind people, since they can be used to test theories on the development of human vision.

In 2009, British researchers used gene therapy to induce the ability to recognize the entire color spectrum in red-green blind squirrel monkeys. The research team hopes that these results will lead to therapeutic approaches to curing color blindness and possibly even blindness.


Prevention of red-green color weakness is not known at the moment because it is an inherited disorder. On the other hand, the red-green weakness is not considered a disease or symptoms that can severely impede a normal and healthy life. From this point of view, prevention of red-green weakness is not necessary.


A red-green weakness cannot be cured and cannot be prevented. It influences the patient throughout his or her life in various aspects of everyday life. For this reason, consistent care by an ophthalmologist is necessary in order to be able to integrate the visual impairment more easily into everyday life.

An improvement or healing of the symptoms is the exceptional case with a red-green weakness. This is especially true when the visual impairment is congenital. An operation is also not possible. However, if a specialist discovers a red-green weakness early on, it can be treated satisfactorily. This is primarily the case with a non-congenital red-green weakness.

Follow-up care aims to improve the patient’s quality of life. This affects not only vision, but also mental health. If the patient perceives his red-green weakness as very stressful or limiting and suffers from it, parallel psychological care is advisable in addition to the ophthalmological check-up. In this way, the development of a depression is prevented.

Particular attention is paid to the ability to drive during aftercare, since a red-green weakness can significantly limit the patient’s participation in traffic. Driving is sometimes impossible. In order to cope better with these and comparable limitations, appropriate exercises are necessary, which the ophthalmologist carries out with the red-green-blind person.

You can do that yourself

People with a red-green weakness can use special lenses that expand or filter the color spectrum. Because these lenses alter color perception, they may not be used while driving or operating certain machines. Some color correction glasses are individually adapted to the degree of ametropia, which means that the red-green weakness can be almost completely corrected.

People suffering from total color blindness may need dark sunglasses. These special glasses have special edge filters that filter certain colors and enhance others. This makes it possible for those affected to read small print and see colors that were previously invisible due to the red-green deficiency.

Patients who suffer from a red-green weakness usually need support in everyday life. The help of friends or acquaintances makes sense, especially in traffic and with fine work. In addition, the patient should consult the ophthalmologist regularly. Mentioned special glasses are just one of many current developments that could enable an almost normal color perception in the future. Depending on the degree of color vision deficiency, the choice of career must be reconsidered. Patients who are ill usually cannot become pilots or train drivers.

Red Green Weakness