Effects of yellow filter glasses on colour discrimination of normal observers and on the illumination level.

Ten healthy young persons wearing yellow filter glasses were examined with the Farnsworth-Munsell 100-hue test using a Macbeth daylight illuminator. Results obtained with (Schott) filters GG 400, GG 420, GG 435 and GG 455 were within normal limits. Using filters GG 475, GG 495 and OG 515 the mean total error score was 123.9, 203.8 and 226.9, respectively, and the test diagram showed a tritan error axis. Illumination of the Macbeth daylight illuminator measured without filters was 1800 lux. Using yellow filters the illumination varied from 1650 to 1500 lux.