The Farnsworth D15 Color Arrangement Test uses the arrangement of specific colour swatches to determine colorblindness. Understanding the different scoring methods can present a challenge, as they can be confusing. The easiest way to learn to score these tests is to interpret your own results using the two scoring methods. The first method uses a graphical presentation to determine your colour interpretation by plotting the colour swatches as you placed them on a line graph and comparing the shape they should take. The second method, called the Vingrys and King-Smith scoring method, uses a more in-depth analysis of angles in colour space to determine colorblindness.
Take the Farnsworth D-15 Color Vision Test online at your decided website (the test is available for free at several Internet sites). Do this by arranging the colour buttons in order according to shade as you see them, starting with the button that is already in place.
Click the "Get Results" button when you are finished with the test to pull up your graphical results and your numerical interpretation of those results.
Look at the line graph drawn on the colour space in the graphical result. If the line follows an elliptical pattern without any lines crossing through it, this indicates that there were no arrangement errors. Lines travelling through the ellipse show that there was an arrangement error, which is common in several types of colour deficiencies (or levels of colorblindness).
Compare the numerical results with the chart provided with your colour vision test to determine the level that your numerical results fall under. For example, if you score an angle of 61.98, a major radius of 8.85, a minor radius of 7.12, a total error of 11.24, an s-index of 1.23 and a c-index of 0.96, your numbers would fall under the normal range, indicating little to no colour deficiency. Note that the range results can vary depending on the test format given, so verify the chart ranges with the test supplier.
Online vision tests are convenient but cannot definitively diagnose a colour deficiency. If you feel that you suffer from a form of colorblindness, make an appointment with an ophthalmologist.