There are different tests available to check your color vision. Unfortunately they can’t be easily compared one to each other. This yields to the question, can you pass one sort of color blindness tests while failing on other ones?

Have you ever heard of somebody who can pass the D-15 test, but can’t pass an Ishihara plate test? I’ve been told I was colorblind (for 20 years) because I can’t see all the numbers in the bubbles. I finally asked my optometrist what type of colorblind I was (out of curiosity) and he gave me the D-15 test to find out. I passed it with flying colors—all in the correct order.

My optometrist has never seen somebody pass the D-15 and fail the Ishihara (he gave me that as well…). Any ideas?

A very important but in some way hidden message in this question is, that you have to go to your optometrist for a reliable check of your color vision. Online color blindness tests are a good start but not the right tool to get secure test results.

Types of color vision deficiency tests

The most common color blindness tests can be arranged into four main categories. In each of those categories are many different types of tests available, whereas the system of the test stays the same.

1. Anomaloscope: The most reliable test which can tell you more about the severity and type of your color blindness. My RGB Anomaloscope shows you someway how an anomaloscope works.
2. Pseudoisochromatic plates: This test category is the most famous one. Invented by Prof. Ishihara they are often called Ishihara plates tests. Based on the idea of colored dots different tests are used.
3. Arrangement tests: This tests are based on differently colored discs which have to be arranged in the correct order. They range from 15 discs (D-15) up to 100 discs.
4. Lantern tests: The most easiest test category developed over 100 years ago. They were originally used to check if you can work for a railway company and distinguish the different signal lights.

When you read through the list above you can easily guess that all those different color blindness tests can’t have the same sensitivity. Some are very sensitive like pseudoisochromatic plates. They are sometimes even not readable for people with normal color vision. On the other side the lantern tests are best to check if you are fit to do certain jobs and are not checking if you are only slightly colorblind.

• Pseudoisochromatic plates, arrangement tests with 100 discs and anomaloscopes are the most sensitive and detailed color vision deficiency tests.
• Looking at arrangement test you will have less sensitiveness with less discs. I don’t make that many mistakes on a D-15 test but I am very much red-blind.
• Lantern tests are not good at testing the severity of your color blindness and are the least sensitive tests.

To conclude: you can easily fail an Ishihara plates tests and pass a D-15 arrangement test at the same time. I would say many people with a low to moderate color blindness will receive such a test result.

What I don’t understand is why your optometrist was astonished by your test results…