Do red objects sometimes look orange, or do blue and purple shades appear almost identical? Difficulty distinguishing certain colours may be a sign of colour vision deficiency, commonly known as colour blindness. Contrary to popular belief, most people with this condition do not see the world entirely in black and white. Instead, they struggle to distinguish specific colours or their shades, particularly red and green. According to the American Academy of Ophthalmology, colour vision depends on specialised cells in the retina that detect light and send signals to the brain. If this process is affected, a person may find it difficult to recognise certain colours accurately.
Genetic Factors Can Cause Colour Blindness
One of the most common causes of colour blindness is a genetic change inherited from parents. According to the National Eye Institute, inherited colour vision deficiency often affects the ability to distinguish red and green. These changes are commonly linked to genes on the X chromosome, which is one reason the condition is more common in men than women. People with inherited colour blindness usually experience the problem from childhood, although they may not realise it until they encounter situations that require accurate colour recognition. In many cases, the condition remains stable throughout life.
Retinal Problems May Change Colour Perception
The retina, located at the back of the eye, contains cone cells that help detect colours. Diseases or injuries affecting the retina can interfere with this process. According to the Cleveland Clinic, certain eye conditions, including age-related macular degeneration, glaucoma and retinal detachment, may affect colour vision. People may notice that colours look faded, less vivid or different from how they appeared previously. If these changes develop over time, an eye examination can help identify whether an underlying condition is responsible.
Optic Nerve Damage Can Affect Colour Vision
The optic nerve carries visual signals from the retina to the brain. Damage caused by inflammation, injury or certain diseases can affect how colours are perceived. Some people may notice that colours appear less bright or that the same object looks different when viewed with each eye. Conditions such as optic neuritis and other forms of optic neuropathy can affect colour vision. New or unexplained changes should be assessed by an eye specialist rather than assumed to be ordinary colour blindness.
Brain Conditions, Medicines and Ageing
Colour perception also depends on how the brain processes visual information. Certain neurological conditions, including multiple sclerosis and Alzheimer's disease, may affect colour vision in some people. Some medicines can also cause changes in colour perception by affecting the retina or optic nerve. Ageing may contribute as well, particularly when cataracts or other eye conditions develop. If colour vision changes after starting a new medicine, consult a doctor before making any changes to the treatment.
How Can You Tell If You Have Colour Blindness?
Common signs include confusing similar shades, struggling to distinguish red from green, finding that colours look unusually dull, or having difficulty identifying colours in everyday situations. However, these symptoms alone cannot confirm colour blindness. An eye specialist may use colour vision tests, including the Ishihara test, which involves identifying numbers or patterns within coloured dots. Most importantly, a problem present since childhood should be distinguished from a sudden change in colour vision. If colours suddenly look different, seek prompt medical assessment to identify the cause.
