Heavy and light smokers have slight differences in chromatic discrimination.

The effects of smoking on color vision have been scarcely studied. To bridge such gap, this study examined if there were differences in chromatic discrimination between heavy and light smokers. The psychophysical Trivector test was used to evaluate chromatic discrimination in healthy controls (  = 36), heavy smokers (  = 29), and light smokers (  = 32). The subject's task was to identify the orientation of the Landolt C ring gap - presented and randomized in one of the four positions (e.g., up, down, right, and left). The thresholds for Protan (red), Deutan (green) and Tritan (blue) were higher in heavy smokers compared to nonsmokers but not to light smokers. The results confirm that heavy smoking and chronic exposure to its harmful compounds affect color discrimination when compared to light smoking; and this is more pronounced in heavy smokers than light smokers. This is particularly important to understand the differences among smokers on visual and multisensory processing.