{"id":1809,"date":"2026-10-20T08:53:00","date_gmt":"2026-10-20T08:53:00","guid":{"rendered":"https:\/\/laseristanbulclinic.com\/eye-glossary\/colour-blindness\/"},"modified":"2026-10-20T12:56:30","modified_gmt":"2026-10-20T12:56:30","slug":"colour-blindness","status":"publish","type":"page","link":"https:\/\/laseristanbulclinic.com\/en\/eye-glossary\/colour-blindness\/","title":{"rendered":"Colour Blindness: What It Is, Types, Causes and Tests"},"content":{"rendered":"\n
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  1. Home<\/a><\/li>
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  4. Colour Blindness: What It Is, Types, Causes and Tests<\/span><\/li><\/ol><\/div>\t\t\t

    Colour Blindness: What It Is, Types, Causes and Tests<\/h1>\n\t\t\t\t\t\t

    Medically reviewed by {{surgeon}}<\/span><\/strong>, {{surgeon’s title and specialty}}<\/span>, on {{review date}}<\/span>. Last updated {{date}}<\/span>.<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t

    \"Illustration<\/figure><\/div>\n\t\t\t<\/div><\/div>\n<\/section>\n\n\n\n\n
    \n\t\t<\/svg>Definition<\/span>\n\t\t\t

    Colour blindness<\/strong> (also colour vision deficiency, or “color blindness” in US spelling)<\/em>: seeing colours differently from most people, so that certain colours are hard to tell apart. Most people who have it are born with it, and the most common type is red-green colour blindness, which mainly affects men. It rarely means seeing in black and white. There is no cure for the inherited forms, but a colour vision test confirms it, and an eye doctor can check whether a later change in colour vision has a treatable cause.<\/p>\n\t\t<\/div><\/div><\/div><\/div><\/section>\n\n\n\n\n

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    Colour blindness: key facts<\/h2><\/div>\n\t\t\t\t\t<\/div>\n\t\t\t
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    <\/svg>How common<\/span><\/dt>
    About 1 in 12 men (8%) and about 1 in 200 women; about 3 million people in the UK and an estimated 300 million worldwide<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Most common type<\/span><\/dt>
    Red-green colour blindness; deuteranomaly is its most common form<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Rarer types<\/span><\/dt>
    Blue-yellow: fewer than 1 in 10,000 people worldwide, men and women equally. Complete colour blindness (achromatopsia): rare<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Usual cause<\/span><\/dt>
    Inherited. Red-green types are carried on the X chromosome<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Can it start later in life?<\/span><\/dt>
    Yes. Eye disease, some illnesses, injury, ageing and some medicines can cause acquired colour vision loss<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Effect on sharpness<\/span><\/dt>
    Red-green and blue-yellow types disturb colour perception but do not affect sharpness of vision<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Diagnosis<\/span><\/dt>
    Colour plate test, hue (arrangement) test or anomaloscope<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Cure<\/span><\/dt>
    None for inherited forms; treating the cause can help acquired forms<\/dd><\/dl><\/div>\n\t\t\t\t
    <\/svg>Specialist<\/span><\/dt>
    Ophthalmologist (eye doctor) or optometrist; at Laser Istanbul Clinic, Prof. Dr. Ahmet Sat\u0131c\u0131, Do\u00e7. Dr. Muhammet Derda \u00d6zer and Op. Dr. Aysan Bayram<\/dd><\/dl><\/div>\n\t\t\t<\/div>\n\t\t<\/div><\/div><\/div><\/section>\n\n\n\n\n
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    How does colour vision work?<\/h2>\n\t\t\t\t\t\t\t\t

    Colour vision depends on cone cells in the retina. The retina is the light-sensitive layer at the back of the eye, and it contains two kinds of light-detecting cell. Rods detect only light and dark and work well in dim light, while cones detect colour and are concentrated near the centre of your vision (American Academy of Ophthalmology, AAO). There are three types of cone, which respond to red, green and blue light, and the brain compares their signals to work out every colour you see.<\/p>\n

    If all three cone types are present and working normally, you have typical colour vision. Colour blindness happens when one type of cone works differently or is missing. The AAO describes the mild form as one where all three cone types are present but one does not work properly, and the severe form as one where cones are absent.<\/p>\n

    Because this is about colour and not detail, red-green and blue-yellow types disturb colour perception without affecting sharpness of vision (MedlinePlus Genetics).<\/p><\/div>\n\t\t\t\t\t\t\t\t\t\t\t<\/div>\n<\/div><\/div><\/div><\/div><\/div><\/section>\n\n\n\n\n

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    What are the types of colour blindness?<\/h2><\/div>\n\t\t\t\t\t\t

    The National Eye Institute (NEI) divides colour vision deficiency into three groups: red-green, blue-yellow and complete. The ending of each name tells you how strong the effect is: -anomaly<\/strong> means a weaker colour signal, and -opia<\/strong> means the signal is missing.<\/p><\/div>\n\t\t\t<\/div>\n\t\t\t

    Type<\/th>What changes<\/th>Severity<\/th>How common<\/th><\/tr><\/thead>
    Deuteranomaly<\/strong> (red-green)<\/th>Certain shades of green look more red<\/td>Usually mild; typically does not interfere with daily life<\/td>The most common type of red-green colour blindness<\/td><\/tr>
    Protanomaly<\/strong> (red-green)<\/th>Certain shades of red look more green and less bright<\/td>Usually mild<\/td>Red-green types as a group affect about 1 in 12 men<\/td><\/tr>
    Deuteranopia and protanopia<\/strong> (red-green)<\/th>Red and green cannot be told apart at all<\/td>Stronger<\/td>Part of the red-green group<\/td><\/tr>
    Tritanomaly<\/strong> (blue-yellow)<\/th>Blue and green, and yellow and red, are hard to tell apart<\/td>Varies<\/td>Blue-yellow defects overall: fewer than 1 in 10,000 people<\/td><\/tr>
    Tritanopia<\/strong> (blue-yellow)<\/th>Blue and green, purple and red, and yellow and pink cannot be told apart; brightness perception is reduced<\/td>Stronger<\/td>As above<\/td><\/tr>
    Achromatopsia (monochromacy)<\/strong><\/th>No colour is seen; clarity of vision may be reduced and bright light is uncomfortable<\/td>Severe<\/td>Rare. The blue cone form is about 1 in 100,000 people<\/td><\/tr><\/tbody><\/table><\/div><\/div>\n\t\t\t
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    What is red-green colour blindness?<\/h3>

    Red-green colour blindness (red-green colour vision deficiency) is the most common type. Reds and greens, and shades made from them such as browns and oranges, are easy to confuse. Depending on whether the red-sensing (protan) or green-sensing (deutan) cones are affected, it is called protan or deutan colour blindness. A search for “red-green vision weakness” or “red-green deficiency” means this condition.<\/p><\/div><\/div>\n\t\t\t\t

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    What is blue-yellow colour blindness (tritanopia)?<\/h3>

    Blue-yellow colour blindness, called tritan colour blindness, is much rarer than red-green: it affects fewer than 1 in 10,000 people, and men and women equally. People with tritanopia confuse blues with greens, purples with reds and yellows with pinks. Because inherited blue-yellow colour blindness is so rare, a new blue-yellow problem in an adult deserves an eye examination, since eye disease can be the cause.<\/p><\/div><\/div>\n\t\t\t\t

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    Does colour blindness mean seeing in black and white?<\/h3>

    Almost never. Complete colour blindness, achromatopsia, where everything looks grey, is the rarest form (AAO, NEI). Most colour blind people do see colours; they just cannot tell some of them apart.<\/p><\/div><\/div>\n\t\t\t<\/div>\n\t\t<\/div><\/div><\/div><\/section>\n\n\n\n\n

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    What causes colour blindness?<\/h2>\n\t\t\t\t\t
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    Inherited colour blindness (present from birth)<\/h3>

    Most colour blindness is genetic, passed from parents to children (NEI). Three genes matter. Two of them, OPN1LW<\/em> and OPN1MW<\/em>, are on the X chromosome and make the red- and green-sensitive pigments. The third, OPN1SW<\/em>, is not on a sex chromosome and makes the blue-sensitive pigment (MedlinePlus Genetics).<\/p>\n

    Why are more men than women colour blind?<\/strong> Red-green colour blindness is X-linked recessive. A boy has only one X chromosome, so a single altered gene on it is enough. A girl has two X chromosomes and is affected only if both carry the change, which is why about 1 in 12 men but only about 1 in 200 women are affected (MedlinePlus Genetics; Colour Blind Awareness). Fathers cannot pass an X-linked trait to their sons, and it is most often inherited from the mother. Blue-yellow and complete forms involve other chromosomes and affect men and women equally (NEI).<\/p><\/div><\/div><\/div>\n\t\t\t\t

    Acquired colour blindness (developing later in life)<\/h3>

    Colour vision can also change after birth. The causes named by the NEI, the AAO and the NHS include:<\/p>\n