Dyschromatopsia in heroin addicts

The Farnsworth-Munsell 100-hue test was employed to determine whether there was any defect of colour vision in 29 confirmed male heroin addicts who had been successfully detoxified. Forty age-matched males served as controls. A typical normal error score on the FM test is about 40 and an error score of over 100 indicates poor colour discrimination; 86.2% of the eyes of the control group had an error score below 100 while only 17.2% of the eyes of heroin addicts had an error score below 100. The colour confusion among the heroin addicts was in the blue-purple (475-495 mu) range. These results indicate that colour vision defects are more common in heroin addicts.