Color blindness

The symptoms of color blindness vary from person to person. Many individuals experience such mild symptoms that they may not even realize they have color blindness. The symptoms may include:

• Difficulty in distinguishing between colors
• Trouble perceiving the brightness of colors
• Inability to differentiate between various shades of red and green or blue and yellow
• Discomfort in the eyes or head when viewing a red or green background
• Worsening of color identification in low light conditions, while colors may be easier to distinguish in natural daylight
• In rare cases, color blindness may impact visual sharpness

The retina, the light-sensitive layer at the back of the eyeball, contains two types of photoreceptor cells: rods and cones. The rods detect lightness and darkness, while the cones detect colors. There are three types of cones that interpret the primary colors: 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, which uses this input to determine our color perception. Color blindness can occur when one or more types of cone cells are absent, not functioning properly, or detect a different color than normal. Mild color blindness occurs when one cone cell does not work correctly, while severe color blindness happens when all three cone cells are absent or defective.

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

Inherited Color Blindness

Most people with color blindness are born with it, known as 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 if the father has the condition but the mother does not.
  • There is a 50% chance of inheriting red-green color blindness or being a carrier if the father has the condition and the mother is a carrier.

Acquired Color Blindness

This type of color blindness mostly develops as a blue-yellow color deficiency and has several associated risk factors, including:

• Aging: The ability to distinguish different colors deteriorates slowly with age.
• Chronic Illnesses: Eye-related diseases such as age-related macular degeneration or glaucoma increase the likelihood of color blindness. Health issues like diabetes, multiple sclerosis, Alzheimer’s disease, autoimmune diseases, high blood pressure, heart problems, nervous disorders, and physiological issues also multiply the chances of color blindness.
• Stroke: Accidents or strokes that damage the retina or affect specific areas 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 vision.
• Industrial and Environmental Chemicals: Exposure to chemicals such as carbon monoxide, carbon disulfide, organic solvents, and some containing lead may increase the risk of color blindness.

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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 taking certain medications.
• Screening tests: The tests for color vision deficiency include:

• Ishihara test: This is the most well-known test for color blindness. A set of images called the Ishihara color plates is used for detection. The individual is asked to look at the images, which have numbers embedded in dots of color. If the person cannot see the numbers, they are likely colorblind.
• Lantern tests: Also known as the Farnsworth Lantern (FALANT) test, this is used to detect individuals who 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: This simple instrument is used to diagnose color blindness. In this test, two different light sources must be matched to the same color. The observer manipulates stimulus control knobs to match two colored fields in color and brightness. This is a standard instrument for diagnosing color vision defects.
• Color arrangement tests: Also called the hue test, the doctor provides blocks of different colors and asks the individual to arrange them in rainbow order, from red to purple. Difficulty in arranging them correctly may indicate a type of color blindness.

There is no way to prevent color blindness that has been present since birth. However, there are opportunities to reduce the occurrence of color blindness later in life by:

• Getting regular eye examinations
• Avoiding risk factors

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Currently, there is no cure for color blindness that is present from birth (inherited color blindness). In many cases, most people with color blindness learn to adapt and live with the condition. If color blindness occurs due to another health problem (acquired color blindness), the doctor will treat the underlying condition. If someone is taking a medicine that causes color blindness, your doctor may suggest altering the dosage if necessary or switching to a different medication.

Here are some ways to work around poor color vision:

• Special glasses or contacts may 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. Originally designed as sunglasses with lenses coated in a special material that exaggerated the wavelengths of light, it was discovered that this coating might help people with poor color vision see differences in pigment, though results vary.

These glasses work by filtering out certain wavelengths of light to help individuals better distinguish red and green colors. While they do not restore normal color vision, they may make certain hues appear more vibrant. EnChroma glasses are now used as color-correcting glasses designed to alleviate symptoms of red-green color blindness, but options are limited and can be expensive.

Contact Lenses

Contact lenses for color blindness are a common choice for many patients, as they are easy to use and painless. If you are concerned about using contact lenses, here is a list of common mistakes that 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 a phone and then tap on the part of the photo to identify the color of that area.

Newer Interventions

Research is ongoing in gene therapy, a technique that uses genes to treat, prevent, or cure a disease or medical disorder, for individuals with inherited color blindness. If modern gene therapy gains approval, it may eventually lead to treatments for color blindness and enhance color vision.

Potential gene replacement therapy for red-green color blindness has already been tested in animals.

Individuals with a severe form of color blindness can face complications such as:

• Achromatopsia: A condition characterized by the partial or total absence of color vision, where the individual cannot perceive colors except black, white, and shades of gray.
• Nystagmus: A condition in which the eyes make rapid, repetitive, uncontrolled movements. In some cases of color blindness, individuals may experience involuntary back-and-forth eye movements.
• Photophobia: Discomfort in bright light, which can occur due to color blindness.

If color blindness occurs as a result of illness or injury, treating the underlying cause may help to improve color blindness. However, there is no cure for inherited color blindness. People with color blindness often consciously apply certain techniques or use specific tools to make life easier 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, natural light.
2. Use of smartphones and apps: With 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
   • Color identification in day-to-day life
3. Look for color blind glasses: This is not a cure for color blindness. However, color-blind glasses are a good option. These glasses are similar to normal glasses and are available in multiple shapes and colors. They work by filtering out the overlapping wavelengths that result in color blindness, helping individuals see the world as a normally sighted person would.
4. Handling challenges in school: If a child is colorblind, coordinate with teachers and ask the following points to help them:
   • 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: If you have difficulty distinguishing between fruits and vegetables due to color, you can search online or ask a worker at your grocery store for help in identifying your favorite items.
6. Cooking tips: For color-deficient individuals, it is difficult to determine if food is fully cooked and ready to eat, or if fruits and vegetables are ripe or rotten. Always follow temperature guidelines while cooking. Instead of relying on the color of the meat, use a meat thermometer to ensure it is thoroughly cooked.
7. Addressing work challenges: Reading and designing PowerPoints, working on graphs and images, and reviewing company documents may pose challenges. A color-blind employee can discuss with their boss ways the company can be more inclusive, such as changing document templates to colors that are easier to comprehend.
8. Dealing with gadgets: Most advanced electronics 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 feature that provides color correction based on the user's specific vision deficiencies.
9. Reading traffic lights: A color-blind person needs to rely on the position of traffic lights rather than the color. For traffic lights that run from top to bottom: the top light indicates stop, the middle light indicates caution, and the bottom light indicates go.

Suggestions for improved traffic lighting: There should be simple tweaks in traffic lights to assist color-deficient individuals in perceiving the signals more easily:

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

These simple ideas can be helpful in assisting color-blind individuals.