Color blindness Also known as Daltonism, Color vision deficiency, Color vision problem.

Overview

Color blindness is the difficulty in telling the difference between certain colors or shades. Very rarely color blindness makes a person unable to see any colors.

Color blindness is mostly an inherited genetic condition. In some cases, it can be acquired in life due to the side effects of certain medications, industrial and environmental chemicals, or chronic illnesses.

Individuals with color blindness encounter some common difficulties in day-to-day life like choosing fresh vegetables, fruits, and flowers, driving a car, and selecting clothes.

Currently, there is no treatment for this condition. However, specific photographic frames eyeglasses and contact lenses can be used to improve the distinguish between some colors.

Key Facts

Usually seen in

  • Individuals between 70 and greater

Gender affected

  • Both men and women but is more common in men

Body part(s) involved

  • Eyes

Prevalence

  • World: 300 million (2023)

Mimicking Conditions

  • Stationary Night Blindness (CSNB)
  • Retinitis Pigmentosa (RP)

Necessary health tests/imaging

Screening tests 

  • Ishihara test
  • Lantern tests 
  • Anomaloscope
  • Color arrangement tests

Treatment

  • Memorizing
  • Special glasses or contacts 
  • Visual aids apps and technology

Symptoms Of Color Blindness 

The symptoms of color vision deficiencies vary from person to person. Many people have such mild symptoms that they don’t even realize they have color blindness. The symptoms of color blindness may include: 

  • Difficulty in telling colors apart
  • Trouble seeing the brightness of colors
  • Inability to distinguish different shades of red and green or blue and yellow 
  • Feeling of eyes or head getting hurt while looking at a red or green background
  • Identification of colors may become worse in low-level light, conversely, colors may be easier to distinguish in natural daylight.
  • In the rarest cases, color blindness may affect the sharpness of vision. 

Causes Of Color Blindness 

The retina (the light-sensitive layer at the back of the eyeball) of the eyes has two types of photoreceptor cells. They are called the rods and the cones. The rods detect lightness and darkness whereas the cones detect colors. There are three types of cones that are able to interpret the primary colors ie. red, green, and blue:

  • Red-sensing cones (L cones): These cones perceive long wavelengths of light (around 560 nanometers).
  • Green-sensing cones (M cones): These cones perceive middle wavelengths (around 530 nanometers).
  • Blue-sensing cones (S cones): These cones perceive short wavelengths (around 420 nanometers).

These cone cells send information through the optic nerve to the brain. The brain then uses this input to determine our color perception.

color vision deficiencies can occur when one or more types of cone cells are absent, not working properly, or detect a different color than normal. Mild color blindness happens when one cone cell does not work right. Severe color blindness occurs when all three cone cells are absent or defective.

Types Of Color Blindness 

The different types of color blindness are:

Red-green color blindness

This is the most common color vision deficiencies that makes it hard for the individual to differentiate between red and green.

There are 4 types of red-green color vision deficiencies:

  • Protanomaly: This leads to reduced sensitivity to red light, and makes the red look less bright. This type is mild and usually doesn’t interfere with normal activities.
  • Deuteranomaly: This leads to reduced sensitivity to green light. This is the most common type of red-green color blindness. This type is mild and doesn’t usually get in the way of normal activities.
  • Protanopia and deuteranopia: In both of these types the individual is unable to tell the difference between both red and green at all. 

Blue-yellow color blindness

This is a less common type of color vision deficiencies in which an individual is unable to differentiate between blue and green, and between yellow and red.

There are 2 types of blue-yellow color blindness: 

  • Tritanomaly: This leads to reduced sensitivity to blue light. 
  • Tritanopia: This is unable to tell the difference between blue and green and yellow and pink. This color blindness makes the color look less bright. 

Blue cone monochromacy 

This is the rarest form of color vision deficiencies. In this type of color blindness, there is a lack of working L cones or M cones. There are only S cones. Individuals having this kind of color blindness often find it hard to tell the difference between colors and see mostly grays. 

Rod monochromacy (achromatopsia)

Achromatopsia is a condition when all or most of the cones are missing or not working properly. This is also called monochromacy, and it’s quite rare. For them, their world consists of different shades of gray ranging from black to white, rather like seeing the world on an old black-and-white television set. An individual may also have other vision issues that may greatly impact their quality of life.

Risk Factors For Color Blindness 

The various risk factors of color blindness can be inherited (a person is born with it) or acquired (developed later in life). The causes are different in each case.

Inherited color blindness

Most people with color blindness are born with it. This is called a congenital condition. A change (mutation) to the genes leads to inherited color blindness. The most common form, red-green color blindness, follows an X-linked recessive inheritance pattern. The genetics for red-green color blindness are:

In males

  • A male baby will have red-green color blindness if the mother has the condition 
  • There is a 50% chance of inheriting red-green color blindness if the mother is a carrier (the mother carries one copy of the genetic mutation but doesn’t have the condition). The other copy is normal, hence there is a 50% chance.
  • The condition would not be present if the father has the condition as the father contributes the Y chromosome to male babies and the X chromosome to female babies. 

In females 

  • A female baby will inherit red-green color blindness if both parents have the condition.
  • The female baby would be a carrier in case the father has the condition but the mother does not. 
  • There will be a 50 percent chance of inheritance of red-green color blindness (50% chance) or a carrier (50% chance) if the father has the condition and the mother is a carrier.

Acquired color blindness

This color blindness mostly develops as a blue-yellow color deficiency, and has many associated risk factors including

  • Aging: The ability to distinguish different colors deteriorates slowly with age.
  • Chronic illnesses: Having eye-related diseases such as age-related macular degeneration or glaucoma increases the likelihood of color blindness. Having health issues like diabetes, multiple sclerosis, Alzheimer’s disease, autoimmune diseases, high blood pressure, heart problems, nervous disorders, and physiological issues multiplies the chances of color blindness. 
  • Stroke: Accidents or strokes that damage the retina or affect a particular area of the brain or eye can lead to color blindness. 
  • Medications: Certain medications for high blood pressure, diabetes, hypertension, erectile dysfunction, tuberculosis, and specific antibiotics and barbiturates, can alter the vision of the eyes. 
  • Industrial and environmental chemicals: Exposure to chemicals such as carbon monoxide, carbon disulfide, organic solvents, and some containing lead may also increase the risk of color blindness.

Diagnosis Of Color Blindness 

Accurately diagnosing color blindness is important to reduce further complications. Diagnosis includes

History 

A complete history provides important information to determine whether the patient has a family history or is having certain diseases and taking certain medications. 

Screening tests 

The tests for color vision deficiency are: 

  • Ishihara test: This is the most well-known test for color blindness. A set of images called the Ishihara color plates is used for the detection of color blindness. The individual is told to look at the images, which have numbers embedded in dots of color. The color of the numbers is a different color than the background. If the person cannot see the numbers, then the individual is probably colorblind. 
  • Lantern tests: This test is also called a Farnsworth Lantern [FALANT] test which is used for detecting individuals that are unable to distinguish between red and green. During this test color pairs (including red, green, and white) are shown and the outcome is based on the number of color-naming errors. 
  • Anomaloscope: A simple instrument anomaloscope is used to diagnose color blindness. In this test, two different light sources have to be matched to the same color. They are optical instruments in which the observer must manipulate stimulus control knobs to match two colored fields in color and brightness. This is a standard instrument for the diagnosis of color vision defects. 
  • Color arrangement tests: This test is also called the hue test. The doctor will provide you with blocks that are different colors. The doctor will ask you to arrange them in rainbow order, from red to purple. If the individual is facing trouble putting them in the correct order, there are chances of having a type of color vision deficiencies.

Prevention Of Color Blindness 


There is no way to prevent color vision deficiencies that has been present since birth. But there are chances to reduce the occurrence of color blindness later in life by getting regular eye examinations and steering clear of avoidable risk factors. 

World Sight Day is observed on 10th October of every year. The aim is to raise awareness of blindness and vision impairment. Are you taking care of your eyes? 

Specialist To Visit

You should contact your doctor immediately if you have the following symptoms:

  • Difficulty in telling colors apart
  • Trouble seeing the brightness of colors


Doctors that can help you diagnose and treat color blindness include:

  • General Physician
  • Ophthalmologist 
  • Optometrist 

An ophthalmologist or an optometrist is a medical practitioner who specializes in eye and vision care. The doctor helps detect any problems related to eyes and vision early.

Treatment Of Color Blindness


Currently, there is no cure for color blindness that is present from birth (inherited color vision deficiencies). In many cases, most people with color blindness learn to adapt and live with the same condition.

If color blindness is happening because of another health problem (acquired color vision deficiencies), the doctor will treat the condition causing the problem. If someone is taking a medicine that causes color blindness, your doctor may suggest altering the ratio if required or switching to a different medicine.

Here are some ways to work around poor color vision:

Special glasses or contacts may also help some people with red-green deficiency see the difference between colors.

EnChroma glasses 

  • These glasses were created for doctors to use during laser surgery procedures. They were originally created as sunglasses with lenses coated in a special material that exaggerated the wavelengths of light. 
  • It was discovered that the coating on these lenses might help people with poor color vision to see the differences in pigment but to varying extents. 
  • These glasses work by filtering out certain wavelengths of light to help people better distinguish red and green colors. The glasses do not help in restoring normal color vision, but they may make certain hues appear more vibrant.
  • These glasses are now used as color-correcting glasses designed to alleviate symptoms of red–green color blindness. But the options are highly limited and expensive to be used by all individuals. 

Contact lenses 

Contact lenses for color blindness are the most common choice for many patients, as it is easy to use and painless too. 

Are you worried while using contact lenses? Here is a list of a few common mistakes which lens wearers should avoid to take care of their eyes.

Visual aids apps and technology 

Certain apps can be used to take a photo with the phone and then tap on the part of the photo to find out the color of that area.

Newer Interventions 

  • Research has been going on gene therapy (a technique that uses genes to treat, prevent or cure a disease or medical disorder) for people who have inherited color blindness. If modern gene therapy does catch on, treatments for color blindness may eventually be approved and could open the door to color vision enhancement.
  • Potential gene replacement therapy for red-green color vision deficiencies has already been tested in animals.

Complications Of Color Blindness 


Individuals with a severe form of color vision deficiencies can face complications like: 

Achromatopsia: It is a condition characterized by the partial or total absence of color vision. The individual cannot perceive colors except black, white, and shades of gray. 

Nystagmus: It is a condition in which your eyes make rapid, repetitive, uncontrolled movements. In some cases of color vision deficiencies, individuals may face involuntary back-and-forth eye movements. 

Photophobia: The discomfort in bright light can be due to color vision deficiencies.  

Living With Color Blindness 


If color blindness occurs as a result of illness or injury, treating the underlying cause may help to improve color vision deficiencies. However, there’s no cure for inherited color vision deficiencies.

People with color vision deficiencies often consciously apply certain techniques or use specific tools to make life easier by 

  • By memorizing the order of color objects 
  • Having a caregiver who can sort the clothing or other items

A few tips that can help in managing everyday challenges: 

1. Aim for right lighting 
Lighting makes a big difference in the abilities of those with a vision deficiency. Yellow or dull lighting can make it even harder to perceive color. Glares can make it difficult to perceive colors properly. In areas where the lighting can be controlled, aim for bright, and natural light.   

2. Use of smartphones and apps
With the help of advancements in technology, smartphone apps can assist people with color vision deficiencies in identifying colors. Certain apps are very useful while shopping or picking out clothes in the morning. The app is mainly designed for color-blind individuals and helps in 

  •  Matching clothes 
  • All sorts of color identification in day-to-day life

3. Look for Color Blind glasses 
This is not a cure for colors blindness. However, colorblind glasses are the best option. These glasses are just like the normal glasses available in multiple shapes and colors. These glasses work by filtering out the overlapping wavelengths that result in color blindness and help in seeing the world as a normal-sighted person and conquering everyday tasks. 

4. Handling challenges in school 
If the child is colorblind coordinate with teachers and ask the following points to help their children: 

  • Let the child sit front and center to have a good view of the blackboard
  • Label paints and other art supplies with basic names 
  • Create handouts that only use black ink on a white sheet of paper

5. Shopping for fruits and vegetables 
Suppose you find difficulties in distinguishing between fruits and vegetables due to color. In that case, you can search online or ask a worker at your grocery store for help in determining your favorite fruits and vegetables. 

6. Cooking tips 
For color-deficient individuals, it is difficult to determine if the food is fully cooked and ready to eat and if fruits and vegetables are ripe or rotten. The best practice to follow is while cooking, always follow temperature guidelines. Instead of determining if a piece of chicken has been cooked thoroughly based on the center of the meat’s color, use a meat thermometer.

7. Addressing work challenges 
Reading and designing Power Points at work, or working on graphs and images and reading company documents may possess a challenge. A color-blind employee can speak with the boss about ways the company can be more inclusive, such as changing company document templates to colors that aren’t as difficult to comprehend. 

8. Dealing with gadgets 
Most advanced electronics these days have ways to signal a low or full battery without relying on color. For example, Apple computers have a setting called “Differentiate without colors.” Android phones also offer a higher version that offers color correction based on what colors the user is not able to see.

9. Reading traffic lights 
For reading the traffic lights a color-blind person needs to rely on the position rather than the color. For traffic lights that run from top to bottom: the top stops, the middle is caution, and the bottom is gone. 

Suggestions for improved traffic lighting 

There should be a simple tweak in the traffic lights to make color-deficient individuals perceive the light easier:

  1. The new traffic lighting system should have two colors for each sign. The “stop” sign should have the center red and a peripheral yellow rim. The “go” sign should have a central green and a peripheral blue rim. Thus most color-blind individuals (red-green) will detect the yellow rim for “stop” and the blue rim for “go”. 
  2. The traffic lights should have only these two signals: “stop” and “go”, eliminating the intermediate orange sign.