Blue and yellow outer color zones on the lower vertical meridian were measured in a Goldmann spherical projection perimeter using three different techniques and four observers.
The limits of the color zones are not smooth but show irregular peaks and dips and do not have sharp cutoffs in sensitivity. The peaks and dips are reliable for any given observer, although they do not correspond between observers.
The method of constant stimuli, the method of limits, and the clinical one-directional technique were compared. The method of constant stimuli is the most reliable method and it gives the most information about the shape and size of the color gradient.
PATRICIA A. KELSEY and IRA SCHWARTZ, "Nature of the Limit of the Color Zone in Perimetry," J. Opt. Soc. Am. 49, 764-769 (1959)