Age and illuminance effects in the Farnsworth-Munsell 100-hue test.

Seventy-five normal volunteers (20-78 yr) were tested on the Farnsworth-Munsell 100-hue test at each of five illuminance levels. Each cap score distribution was analyzed by fitting a two-cycle sine wave whose amplitude and phase characterize the polarity of the error distribution and its axis. Analysis of these parameters reveals a similarity between tritanlike defects in older groups and those of younger groups at lower illuminance levels. These data are also useful for specifying age norms for the polarity of the error distribution.