Most people who are colour blind don't find out from a doctor. They find out from a school test, an army medical, or a colleague pointing out that two wires or two graph lines look identical to them and no one else. About 1 in 12 men and 1 in 200 women have some degree of colour vision deficiency, often unnoticed for years since daily life rarely demands precise colour judgment. The cause comes down to the retina's cone cells: three types, tuned to red, green, and blue light, and colour blindness happens when one or more isn't working right. The inherited form has no cure, but colour-filtering glasses and a few smartphone apps can make daily tasks easier.
Dr. Vaishal Kenia, Chairman and Medical Director at Eye Hospital in Mumbai, explains: "A lot of patients walk in worried their whole eyesight is failing, when really it's much more contained than that. You can have 20/20 vision and still mix up red and green in dim light. Once patients get that, the rest of the conversation, what treatment can realistically do and what it can't, tends to go a lot smoother."
What Causes Colour Blindness?
Ask most people and they'll point to genetics, and they're right, at least for the inherited kind. It's carried on the X chromosome, so it turns up in men far more than women. A mother might carry the gene her whole life without a single symptom and still hand it down to her son. Red-green mix-ups cover most of these cases.
- Inherited colour blindness is the one most people have heard of. It's tied to a gene on the X chromosome, which is why men are affected far more often than women. A mother can carry the gene without a single symptom herself and still pass it to her son. Red-green confusion makes up the bulk of these cases.
- Then there's acquired colour blindness, which shows up later in life and has nothing to do with genetics. Ageing plays a role, and so do conditions like cataracts, diabetic retinopathy, and glaucoma. Certain medications can trigger it as well.
- Damage to the retina or optic nerve can throw off colour perception before anything else feels wrong, which is one reason a full retinal exam usually matters more than a quick colour chart.
- Not everyone loses colour the same way. Some people only miss a narrow slice of shades. Others lose a lot more, depending on how many cone types are involved and how badly.
How Is It Tested, and Can It Be Corrected?
- The Ishihara test is probably one you've already taken without realizing it, tucked into a school eye check or a licence exam. Coloured dots hide a number inside the plate, and if someone has red-green deficiency, they'll often call out a different number than what's actually there, sometimes nothing at all.
- Acquired colour blindness gets a closer look than a chart alone can give. Doctors bring in tools like OPD Scan III and OCT to work out whether something in the retina or optic nerve is driving it, and that answer shapes whatever comes next.
- As for correction, colour-filtering glasses tend to come up first. The tinted lenses stretch out the difference between certain wavelengths, so shades that used to blur together separate more clearly. They're not a fix, colour vision underneath stays the same, but a lot of wearers say everyday things like reading a traffic light get noticeably easier.
For anyone curious about how retinal issues can affect vision more broadly, our earlier post on retinal detachment warning signs is worth a look, since some of the same structures come up.
Why Choose Kenia Eye Hospital?
Kenia Eye Hospital has been running out of Santacruz (West), Mumbai since 1998, and the diagnostic setup goes well past a standard colour chart. A comprehensive eye exam here draws on OPD Scan III, OCT, and detailed retinal imaging to confirm or rule out an underlying cause when colour vision changes later in life, rather than treating it as a one-off screening. For kids, colour vision checks are available through the squint and paediatric clinic, and it's worth doing before school starts if there's any family history.
The hospital is NABH, QAI, and FEQH accredited, and empanelled under CGHS. Call +91 75064 99962 or book a consultation to have a specialist take a look.
