Identification of colour thresholds in persons with damage of chiasma opticum
Our objective was to estimate the colour-contrast-sensitivity (CCS) thresholds in persons with damage of chiasma opticum. Twenty-three persons with various sizes of pituitary adenoma (PA) and fifty age-matched controls were tested. Correlation was made between the CCS thresholds and the size of PA, which affects the chiasma opticum. The subjects were shown a computer-generated stimulus, consisting of a line surrounded by grey background. The line colour saturation was varied by increasing or decreasing its red, green, or blue phosphor luminance starting from the initial grey of the background. The subjects judged the orientation of the line and it was defined in terms of distance between colour of the line and the background in the L*, a*, b* system of coordinates (CIE, 1976). The mean CCS in group PA with less than 1 cm was 1.8, in group PA with more than 1 cm was 3.5, and in the control group was 1.4. The difference between the means of colour thresholds in persons with PA and controls was significant ( p<0.001). We found strong correlation between the size of PA and CCS changes in persons with damage of chiasma opticum.