NDA Colour Blindness Test 2026: CP-I, CP-II and CP Pass Explained

The Indian Armed Forces use a three-tier Colour Perception (CP) grading system to assess how well a candidate's colour vision meets the demands of their role. Different branches and duties require different grades. Here is what each grade means:

The grading reflects the operational demands of each service. Pilots need to identify aircraft warning lights, runway signals, and navigation beacons in all lighting conditions — hence the strictest standard. Army officers need to read maps, identify vegetation, and operate communication equipment — near-normal colour vision suffices. Naval officers on surface vessels have slightly less demanding colour recognition requirements for most roles, though naval aviation parallels Air Force standards.

Understanding your specific type of colour vision deficiency helps you predict which CP grade you might meet. The following are the main categories:

• Deuteranomaly / Deuteranopia — The most common form, affecting roughly 6% of males. A red-green deficiency where green cones are shifted or absent, causing green to appear similar to red. Deuteranomaly is a partial deficiency (anomaly); deuteranopia is the complete form. This is the type most people mean when they say "colour blindness."
• Protanomaly / Protanopia — Also a red-green deficiency, but affecting the red cones. Red appears dark or indistinct. Protanopia (complete form) renders red essentially invisible against dark backgrounds — a significant safety hazard in signal-reading contexts.
• Tritanomaly / Tritanopia — A blue-yellow deficiency affecting the short-wavelength (blue) cones. Rare and less likely to cause problems on standard Ishihara testing, which focuses on red-green discrimination.
• Achromatopsia — Complete colour blindness. Extremely rare. All colour information is absent; the world is perceived in shades of grey. Any candidate with achromatopsia will be unfit for all three wings on colour vision grounds.

The vast majority of candidates who discover they have a "colour problem" have deuteranomaly — a partial, mild red-green deficiency. Many of them will pass the Ishihara test and qualify for CP-II or CP Pass. The Ishihara plates are specifically designed to detect red-green deficiencies; they are less sensitive to blue-yellow (tritan) defects.

The practical mapping of colour vision severity to NDA wing eligibility is as follows:

Key takeaways: Air Force Flying requires CP-I — no colour vision deficiency of any degree is acceptable. Army (CP-II) and Navy (CP Pass) allow candidates who can pass the Ishihara test. However, borderline cases at the SMB may be referred to the AMB or RMB for more detailed Anomaloscope or Farnsworth D-15 testing, where results may differ from a basic Ishihara screen.

The Ishihara pseudoisochromatic plate test is the standard colour vision screening tool used at the Service Medical Board (SMB). Here is how it works in practice:

• The test consists of a series of circular plates, each containing a pattern of coloured dots. Hidden within the pattern is a number or a curved line that a person with normal colour vision can read easily.
• Someone with a red-green deficiency will either see a different number, see no number at all, or see a different tracing path.
• Plates are typically shown in a standardised lighting environment. You read each plate aloud; the examining medical officer records your response.
• There are transformation plates (where colour-blind persons see a number that normal-vision persons cannot) to detect exaggeration or malingering.
• At the SMB, the Ishihara is the primary screening test. Candidates who show deficiency, or where there is doubt about the result, may be referred to the Air Force Medical Board (AMB) or Review Medical Board (RMB) for additional testing with the Anomaloscope.

The Anomaloscope (Nagel type) requires the candidate to match an orange field by mixing red and green light — it provides a precise, objective measurement of the type and severity of any red-green deficiency. It is the gold-standard test for CP-I assessment.

Night blindness (nyctalopia) is a distinct visual condition from colour blindness and is tested separately at the medical board. The two conditions are unrelated in cause and mechanism.

For all flying candidates (Air Force, and naval aviation), a certificate from a medical centre regarding night vision is required per the notification (Appendix D / AFCAT para 28). Candidates with documented night blindness are unfit for flying duties, regardless of their colour vision status.

Colour vision is only one component of NDA visual standards. Other permanent visual disqualifiers include:

• Uncorrected visual acuity below the required threshold for your wing
• Manifest squint (strabismus)
• Nystagmus
• Diplopia (double vision)
• Keratoconus
• Progressive myopia
• Retinal disease or detachment

See the full eyesight requirements guide for complete visual acuity standards by wing, spectacles policy, and LASIK eligibility.

If you are concerned about your colour vision, the most useful step before your medical board is to get tested by an optometrist or ophthalmologist:

• Get an Ishihara test first. Most optometry clinics and eye hospitals offer this at low cost. If you pass the Ishihara (common 24-plate or 38-plate edition), you very likely meet CP-II and CP Pass standards, covering Army and Navy eligibility.
• For Air Force Flying certainty, get a full workup. An Anomaloscope test at an ophthalmology clinic (government medical college hospitals typically have this equipment) will give you a precise assessment of whether you meet CP-I standards. This is important because mild deuteranomaly that passes Ishihara may still fail the Anomaloscope, which is used at the AMB for flying-branch candidates.
• Do not attempt to memorise the Ishihara plates. Medical boards are trained to detect this. Additionally, transformation plates and other verification methods are built into the standard test sequence.
• Declare honestly during the medical. Failing to disclose a known condition constitutes a false declaration — a disqualifying offence with consequences beyond the medical rejection.