Colour blindness red, green |Test for colour blindness

 Colour Blindness

The inability of seeing color in a normal way is known as Colour blindness. Colour blindness is also known as color deficiency. It happens when someone did not recognize certain color. This usually happens between the color like red, green, and blue. 

This diagnostic test will help to determine if you suffer from red-green color blindness. Can you identify the following numbers?  if you had difficulties in identifying the numbers you may be suffering from red-green color blindness and should consult with an optometrist.

In the retina, we have two types of cells that detect light and color. They are rods and cones. Rods only detect light and dark which are sensitive to low light levels. whereas cones detect color and are concentrated near the center of vision. There are three types of cones that detect color: Red, Green, and Blue.

Symptoms

The symptoms of color blindness range from mild to severe. Most of the people did not recognize the color deficiency due to mild symptoms. Parents or teachers may notice a problem of a child when he/she is learning the color.

1. The trouble of seeing colors and the brightness of color in the normal way.
2. The inability of telling the difference between shades of similar color.

Talking about the severe condition of color blindness, as usually, they don't affect the sharpness of vision. The difficulty of seeing any color at all and seeing everything only in shades of gray is known as Achromatopsia. 

The severe condition is often associated with:

1. Amblyopia(Lazy eye)
2. Light sensitivity(photophobia)
3. Poor vision

Causes

• Most of the children are born with color blindness due to a partial or complete lack of cones in the retina. It is known as Congenital color deficiency.
• Some color blindness occurs later in life due to

1. Disease
2. Trauma
3. Vascular disease
4. The toxic effect of drugs

Risk factors

The certain conditions that may increase the risk of acquired color deficiency are:

1. Glaucoma
2. Diabetic Retinopathy
3. Macular Degeneration
4. Leukemia, etc.

Diagnosis

Your ophthalmologist will conduct a simple test to determine if you have color blindness or not.

Your doctor will show a pattern made up of multi-colored dots. If you don't have color deficiency then you will be able to see numbers and shapes among the dots. If you have a color deficiency it will be difficult for you to find the number or shape in the pattern.

Treatment

Usually, there is no treatment for congenital color blindness. Normally, it does not cause any significant disability. As there are some special contact lenses and glasses that can help you.

 How do we perceive color?

Color vision works by using cells called cones that are located within the retina of the eye. Humans are trichromats meaning they have three types of cones that are sensitive to different colors of light. 

• The "S" cones are sensitive to blue light. 
• The M cones are sensitive to green light and
•  The L cones are sensitive to red light

 Color blindness occurs when the cone cells don't function properly. There are three overarching forms of color blindness monochromatism is the absence of all three cones resulting in the inability to perceive color. Dichromatism is the presence of only two cones. Anomalous trichrome 'it is ax men all three cones are present but color perception is typical. Red-green color blindness falls into the categories of dichromat ISM and anomalous trichrome.

It is scientifically referred to as protanopia/protein amélie and deuteronopia / Deuter a nomaly protanopia is the loss of red L cones resulting in only green-blue color perception and deuteranopia is the loss of green M cones resulting in red-blue color perception. 

 According to birch in 2012 the overall prevalence of red-green color blindness is approximately 8% in men  and 0.4% in women that are European Caucasians 5% male Asians and 4% male Africans.

 These are chromosomes,  human beings have 23 pairs of chromosomes the last pair is called sex chromosomes as they determine an individual's sex, XY represents males whereas, XX represents females. Chromosomes are structures that contain genes and genes contain instructions that are responsible for the development of cells tissues and organs.  Studies show that red-green color blindness is due to an atypical X chromosome. 

As a result, the prevalence of this condition is higher in males compared to females because as x-linked recessive since males have One X chromosome and females have two this means that males are more susceptible to the condition for a female to express the red-green colorblindness phenotype both of their x chromosomes must be affected. If only one x chromosome is affected and they have termed a carrier and don't display the phenotype but are capable of passing down the condition to their children.

Although people with red-green color blindness can live relatively normal lives there are some limitations. Those suffering from the condition cannot choose certain career fields such as police enforcement, firefighting, and piloting.

Written by Barsha Panth