Farnsworth Lantern Test

What is a Farnsworth Lantern?

The Farnsworth Lantern is a very old piece of equipment used to detect color blindness. As most color blindness is red-green, it can detect moderate to severe red-green color blindness. Historically it was developed by Commander Farnsworth in the US Navy during World War II and adopted by the US Navy in 1954 for color vision testing for sailors. It was subsequently adopted in flying.

It is a color vision test of only 3 colors (red, green, and white) which you may be required if you fail the Ishihara color test during your medical (all Classes). The Ishihara color test is best for detecting any type of color blindness. The Farnsworth Munsell 100 Hue test is a more comprehensive color test of color blindness. https://www.colorblindtest.net/farnsworth-lantern-test/

What does the test involve?

It consists of 9 pairs of colored lights in different combinations shown for 2 seconds each. If the color deficiency is mild, some patients can still correctly identify the colors. The white light (which looks yellowish) has a 50% neutral grey filter to reduce differentiation based on luminance. The pairs of lights are presented randomly so that patients cannot memorize them.

The lights can be presented as a round of 9 pairs or a round of 18 pairs (each pair being shown twice). Correct identification of the lights in either round will constitute a Pass. To pass the test, no errors are permitted in a round of 9 pairs, or a maximum of 2 errors in a round of 18 pairs.