Nagel test

Na·gel test

(nah'gĕl),
a test for color vision in which the observer determines the relative amounts of red and green necessary to match spectral yellow; an instrument called a Nagel anomaloscope is used.

Na·gel test

(nā'gel test)
A test for color vision in which the observer determines the relative amounts of red and green necessary to match spectral yellow; an instrument called the Nagel anomaloscope is used.

Nagel,

Willibald A., German ophthalmologist and physiologist, 1870-1911.
Nagel test - a test for color vision.