Influence of illumination on results of the hue-discrimination test, Roth 28-Hue desaturated

Objectives: To study the influence of different illumination levels on the results of the hue-discrimination test, Roth 28-Hue desaturated. Subjects a nd methods: The cap-sorting test, Roth 28-Hue desaturated, was conducted us ing four different illumination levels and four groups of patients taken fr om a total test cohort of 172 ocularly and generally healthy subjects: 4800 lux (Group I: 76 subjects; mean age+/-SD: 30+/-9 years); 2000 lux (Group 2 : 35 subjects; mean age+/-SD, 31+/-5 years); 1000 lux (Group 3: 34 subjects ; mean age+/-SD: 31+/-8 years); and 1000 lux (Group 4: 26 subjects; mean ag e+/-SD: 30+/-7 years). The illumination levels were determined with the Min olta Chroma Meter XY-I, Illumination was provided by fluorescent light sour ces with a balanced spectral distribution and a color-rendering index of 93 (Osram L36W/12 LDL Daylight), Results: No differences could be detected be tween the illumination level of 4800 lux (average error sum=median+/- MAD; 42+/-18) and 2000 lux (average error sum: 40+/-22). However, examination wi th 1000 lux showed a small increase in the average error sum (52+/-21) and the examination with 1000 lux showed a statistically significant increase i n the average error sum (78+/-20)(Wilcoxon, p<0.001) but without a preferre d disturbance of any particular color axis. Discussion: These differences i n error score demonstrate that the results of hue-discrimination tests can be influenced by the illumination level. This must be considered when the r esults of different color tests are compared. As a standard, we recommend a n illumination level of 2000 lux.