All tests were performed according to the same procedure
in a quiet room beneath the work place. We used a selfconstructed
gray box with a daylight lamp (Osram L18W
/
72
Biolux, color temperature 6500 K, illumination 900 lux). The
eyes were examined separately with the Farnsworth panel
D-15 test (Luneau, Paris) (11), the Lanthony desaturated
panel D-15 test (Luneau, Paris) (20), and the Standard
Pseudoisochromatic Plates part 2 (SPP2-test) (14). The panel
tests were viewed at a distance of 50 cm and the plates at a distance
of 75 cm. There were no time limits for the panel tests.
After having finished each panel test, the subjects were told to
proof the arrangement of the caps. On each plate of the SPP2
test two figures are to be recognized. The subjects were also
asked if they could better recognize the left or the right figure.
Each plate was demonstrated for 5 s.