How Common Is Color Blindness In Women?

Introduction

According to the National Eye Institute, colour blindness, or colour vision deficiency, is the inability to see certain colours, brightness of colours, or differentiate between different shades of colour, mainly red and green, but also blue and yellow. 

Understanding colour blindness is very important because it can have a strong impact on a person’s entire life and career.¹ In fact, colour blindness can influence a person’s relationships, education, and food choices. It can even limit their career should they choose to apply to become pilots, electricians, or graphic designers. 

It is even more important to understand the prevalence of colour blindness in people assigned female at birth (AFAB), in particular because, coupled with the reasons above, they are less likely to be colour blind compared to people assigned male at birth (AMAB). In turn, this may result in colour blind people AFAB receiving delayed diagnosis or not being diagnosed at all, as well as feeling under-supported, misrepresented, misunderstood and neglected. In fact, according to a recent survey conducted by EnChroma, 81% of colour blind people AFAB believe that they experienced more challenges compared to their counterparts before they were diagnosed or suspected of having colour blindness. The survey also showed that 66% of people AFAB with colour blindness were teased and bullied in school for their condition.  

Prevalence of colour blindness in women

Statistics from research studies

According to research studies, colour blindness, particularly red-green colour blindness, affects only 1 in 200 women (0.5%) worldwide.³

Difference in prevalence between men and women

In contrast to women, 1 in 12 men (8%) have red-green colour blindness, making colour blindness more prevalent in men than women worldwide.^2,3 

Types of colour blindness

There are 3 different types of colour blindness including:⁴,⁵ 

1. Red-green colour blindness: 

This is the most common type of colour blindness, and has 4 different subtypes including: 

• Deuteranomaly: This is the most common type of red-green colour blindness. It makes green shades appear more red
• Protanomaly: This type makes red shades appear more green
• Protanopia: Causes difficulties in perceiving red light. Therefore, affected people have trouble distinguishing between red and green, as well as red and black
• Deuteranopia: Causes difficulties in perceiving green light. Therefore, affected people have trouble distinguishing between red and green, as well as yellow and darker shades of green

2. Blue-yellow colour blindness: 

This type of colour blindness is less common and has 2 subtypes:⁴,⁵

• Tritanomaly: Causes affected people to have trouble distinguishing between blue and green, as well as yellow and red
• Tritanopia: Causes affected people to have trouble distinguishing between blue and green, purple and red, as well as yellow and pink

3. Total colour blindness (or ‘’monochromacy’’):

 This is the rarest and least common type of colour blindness. The affected people cannot see any colours at all and instead, see everything in different shades of grey. 

Frequency of each type in women

Although the 3 different types of colour blindness affect women at different rates, it is suggested that 0.5% (1 in 200) of women are affected by any type of colour blindness worldwide. 

Causes of colour blindness in women

Genetics and inheritance patterns

Typically, biological females are born with 2 (XX) X chromosomes (match-like structures that contain genes) whilst biological males are born with 1 X and one Y (XY) chromosome from each parent.   

The type of colour blindness a woman inherits depends on whether the genes:

• Are expressed on the sex chromosomes (X and Y) or non-sex linked chromosomes (autosomes)
• Are dominant (one mutated gene copy is needed) or recessive (two mutated gene copies are needed)

For example, red-green colour blindness is inherited in an X-linked recessive pattern. Therefore, men are more likely to have red-green colour blindness because they only need to have the gene expressed on 1 X chromosome, in contrast to women who would need to have the gene expressed on both X chromosomes (uncommon) to be colour blind. 

Blue-yellow colour blindness and total colour blindness, on the other hand, are not passed down via the X chromosome. Instead, blue-yellow colour blindness, for example, is inherited in an autosomal dominant pattern (non- sex-linked). This means that, unlike red-green colour blindness, women would need only 1 mutated copy (dominant) of the blue-yellow colour blindness gene from an affected parent to be colour blind. 

Therefore, men are more likely to have red-green colour blindness and blue-yellow colour blindness. Total colour blindness affects both women and men equally. 

Other causes such as ageing and eye diseases

Although most women are born with colour blindness (genetic), colour blindness can also occur later in life (acquired) due to damage to the eyes or a part of the brain that helps visualise and perceive colour. This can be a result of:⁵

• Eye diseases: e.g. macular degeneration 
• Brain and nervous system diseases: e.g. Alzheimer’s disease
• Medications: e.g. Plaquenil or hydroxychloroquine to treat rheumatoid arthritis

Symptoms of colour blindness in women

Signs and symptoms to look for

The main signs and symptoms of colour blindness in women include difficulties in:⁵

• Distinguishing between certain colours or different shades of colour e.g. red and green or yellow and blue
• Perceiving the brightness of certain colours e.g. red appears less bright (dark grey)

Impact on daily life and potential challenges

As stated above, women with colour blindness can face a lot of challenges in their daily lives. After all, vision is one of our most important senses, allowing us to fully experience and perceive the world. 

The degree of the impact depends very much on the type of colour blindness and how severe it is.

Women with mild colour blindness live normal lives, however, those with severe cases face immense challenges in almost every aspect of their lives including personal, social, professional and romantic. 

Diagnosis and treatment

How colour blindness is diagnosed

An eye care provider will diagnose a suspected person with colour blindness by performing a variety of standard tests during an eye exam. Evaluating both vision and eye health, these tests include: 

1. Ishihara test (also known as ‘’colour plate test’’ or ‘’colour vision test’’): this is the most common type of test used to diagnose red-green colour blindness. The test involves showing the suspected patient multiple colour plates that each contains a pattern of small dots with differently coloured numbers or shapes in the middle
2. Visual acuity: This test involves covering the eyes of the suspected patient one at a time and asking them to read letters from an eye chart (Snellen chart), with or without the aid of a device with several lenses called a phoropter

Available treatments and management strategies

Available treatments

Unfortunately, at present, there is no cure or treatment available for people with inherited colour blindness.

Acquired colour blindness, on the other hand, may be treated by tackling any underlying health conditions and/or using certain medications. 

Management strategies

There are certain devices and technology that can help manage colour blindness (both inherited and acquired) including:¹,⁵

1. Colour blind glasses and contacts: specifically, EnChroma glasses which have been demonstrated in a 2020 study to help people with anomalous trichromacy distinguish between bright and saturated colours due to the high contrast of the filters
2. Visual aids and visual apps

Summary

Also referred to as colour vision deficiency, colour blindness is the inability to:

• See certain colours 
• Differentiate between different shades of colour
• Perceive bright colours

Colour blindness has 3 different types: 

1. Red-green colour blindness: most common 
2. Blue-yellow colour blindness: less common 
3. Complete colour blindness: least common 

The prevalence and frequency of any of the 3 types of colour blindness in women is about 0.5% worldwide. Men are more likely to have red-green colour blindness as opposed to women because the gene for red-green colour blindness is an X-linked recessive gene and men have only 1 X chromosome whilst women have 2 X chromosomes. 

Blue-yellow colour blindness and complete colour blindness, on the other hand, affect both men and women equally as they are passed down via autosomes (non-sex-linked chromosomes). 

Despite colour blindness having a higher prevalence and frequency in men compared to women, women with colour blindness believe they face far more challenges due to:

• Experiencing discrimination
• Receiving little to no support 
• Being left for years to struggle and ponder the reasons behind their symptoms and/or poor educational experiences

It is, therefore, crucial to understand the prevalence of colour blindness in women and raise awareness on the matter. A colour-blind person often receives a diagnosis via an Ishihara test and/or visual acuity during an eye exam. Treatment depends on the form of colour blindness; inherited forms cannot be currently treated whilst acquired forms may be treated by tackling any underlying health conditions. 

Management strategies for colour blindness involve the use of colour-blind glasses (EnChroma glasses) or visual aids.