Colour blindness is one of those conditions that tends to get discovered almost by accident. A child struggles to tell the red and green crayons apart. A young man keeps failing the railway medical. A teenager is confused about which wire in electronics class is which. Suddenly there is a name for something that has been there all along.
What usually happens next, though, is not enough. A basic test is done — most commonly an Ishihara plate test, the one with the circles of coloured dots — a number is missed, a box gets ticked, and the person is told they are colour blind. End of conversation. They leave without knowing which type they have, how severe it is, whether it might affect specific careers they are considering, or whether there are any options.
The testing matters enormously, and not all testing is equal.
What you are actually testing for
Colour blindness is not one condition. It is a family of them. The most common forms are red-green deficiencies — which include protanopia (reduced sensitivity to red), deuteranopia (reduced sensitivity to green), and their milder variants, protanomaly and deuteranomaly. Blue-yellow deficiency (tritanopia) is rarer. Complete colour blindness, where the world is seen in greyscale, is rarer still.
Each of these sits on a spectrum of severity, from mild anomalous trichromacy — where colour perception is shifted but largely functional — to complete dichromacy, where an entire category of colour is effectively invisible. A person with mild deuteranomaly and a person with deuteranopia are both “red-green colour blind” by a common shorthand, but their actual experience of the world is quite different, and so are the implications for careers and daily life.
A good diagnostic workup tells you which type, and how severe. A single plate test does not reliably give you either.
Why most testing stops too soon
The Ishihara test — plates of dots in which numbers or paths are embedded — is genuinely good at one thing: screening. It will reliably tell you whether a red-green deficiency is likely present. It is fast, inexpensive, and widely used. Most clinics, school eye camps, and pre-employment medicals use nothing else.
But it does not tell you the type of deficiency precisely. It does not quantify severity. It does not assess blue-yellow deficiency. And critically, it does not tell you whether someone meets the colour vision standards required for specific aviation, railway, maritime, or defence roles — each of which has its own certified testing protocol.
If you have been told you are colour blind after a quick Ishihara screen and that is where the conversation ended, you have not had a complete assessment.
What a comprehensive assessment looks like
At Sanjeevan, the colour blindness testing facility runs through a battery of internationally recognised tests, covering different aspects of colour vision deficiency — from initial detection all the way through to the precise quantification required for professional certification. Here is what each test in the panel does, and why it is in the panel:
Ishihara Test (Japanese Edition)
The starting point in most colour vision assessments — 38 plates in which numbers and paths are embedded in fields of coloured dots. It will detect the presence of a red-green deficiency quickly and reliably. The Japanese edition is the original, standard form of the test.
Edridge Green Lantern Test
Developed in the early 20th century and officially adopted in Great Britain in 1915, this test simulates coloured signal lights through rotating filters that replicate varying weather and atmospheric conditions. It is particularly relevant for occupations where accurate identification of signal lights matters — rail, aviation, maritime.
Farnsworth Lantern Test (FALANT)
The standard colour vision test used by the United States military and naval services. Like the Edridge Green, it simulates coloured signal lights, but using the specific colour pairs and conditions defined by US defence standards. Relevant for anyone applying to or working in fields with US-aligned certification requirements.
Farnsworth D-15 Test
Rather than numbers or signals, this test uses 15 coloured caps that must be arranged in sequence according to hue. It screens for both red-green and blue-yellow deficiencies and gives a clear picture of the axis of the colour confusion — which direction the deficiency runs. Not a measure of acuity, but of deficiency type.
Oculus HMC Anomaloscope
This is a precision instrument. Using the Rayleigh equation (for red-green) and the Moreland equation (for blue-green), it gives a microprocessor-controlled, quantified diagnosis of colour vision in both axes. It is the most technically rigorous way to determine exactly what kind of deficiency someone has and how pronounced it is. The HMC Anomaloscope is not a screening tool — it is a diagnostic one.
HRR Chart Test
The Hardy-Rand-Rittler charts test colour vision across multiple deficiency types — red-green and blue-yellow — using pseudoisochromatic plates similar in principle to Ishihara but broader in coverage. Useful for classifying deficiency type and severity when the Ishihara alone is insufficient.
Farnsworth 100 Hue Test
A significantly more involved version of the D-15, using 85 coloured caps spanning the full Munsell colour system. It tests the ability to detect and arrange minute differences in hue across the entire visible spectrum. This is not just a test for deficiency — it measures overall colour discrimination ability. It is used in professional contexts where fine colour judgement matters, including some aviation and design-related assessments.
City University (London) Test
Derived from the D-15 arrangement test, this is a plate-based test where, for each plate, one of four surrounding dots must be matched to a central reference dot by hue. It is well-suited to identifying deficiency type and approximate severity, and has been validated extensively in clinical settings.
CAD Test (Colour Assessment and Diagnosis)
This is the most important item in the panel. The CAD test is considered the gold standard in colour deficiency testing — it is the primary requirement for certification by the JAA (Joint Aviation Authority, Europe) and several other government and private aviation bodies worldwide. Sanjeevan holds the first and only CAD machine in India, and one of very few in the world. If you are seeking aviation medical certification for colour vision — whether for a commercial pilot licence, air traffic control, or aircraft maintenance engineering — this is the test that matters, and until now there has been no option to take it within the country.
The panel also includes tests developed by Dr. K.K. Goyal and Dr. Suman Goyal themselves, built from years of clinical experience and in-house research — designed to capture aspects of colour vision that the standard international tests leave unaddressed.
Where to go in Mumbai and What to Expect
Sanjeevan operates majorly from Mumbai:
Chembur
Plot No. 82, Gurushiva, 3rd Floor, Near Swami Vivekanand School, Sindhi Society, Chembur, Mumbai — 400071
WhatsApp / Mobile: +91 93242 40702
Appointments can also be made through sanjeevan.in or by calling the clinic directly.
The full testing panel takes time — this is not a five-minute screen. You will go through multiple tests in sequence, each targeting a different dimension of colour vision. testing is done under specific, controlled lighting conditions, so the results are not comparable to anything done on a screen or phone app. The tests are not stressful, and most adults and older children can complete them without difficulty.
If the purpose of your visit is aviation or defence certification, it is worth calling ahead to confirm which specific tests are required by the relevant authority, so the appointment can be structured accordingly.
A lot of people — particularly those who have failed a quick Ishihara at a pre-employment medical — assume that colour blindness is a fixed, binary verdict with no nuance and no recourse. That is usually not an accurate picture. The type of deficiency matters. The severity matters. The specific requirements of the career or role in question matter. And in some cases, a proper quantitative assessment changes the outcome entirely compared to a failed plate screen.
The testing exists to give you an accurate picture, not just a label. That is the point of doing it properly.
