Impaired color vision in cocaine-withdrawn patients

Background: The main reinforcing effect of cocaine happens by altering dopaminergic neurotransmission in the brain reward systems. Dopamine is found in high concentrations in the retina in which it plays an important role in color vision. Therefore, we investigated whether cocaine-dependent patients might have impaired color vision. Methods: We compared patients recently withdrawn from cocaine (n=31) with matched normal controls (n=31) on 2 color vision tests. Results: Cocaine-withdrawn patients had significantly higher error scores than matched controls on the Farnsworth-Munsell 100-hue and Lanthony desaturated D-15 color vision tests. Also, 23 of the 31 cocaine- withdrawn patients had blue-yellow color vision losses on the Farnsworth- Munsell 100-hue test compared with 3 controls (P<.001, χ² test) and 15 had blue-yellow color vision loss on the Lanthony desaturated D-15 test compared with 2 controls (P<.001 χ² test). Conclusions: These significantly higher test error scores and blue-yellow color vision losses suggest that color vision is impaired in cocaine-withdrawn patients. Color vision testing may be useful in future studies of cocaine-dependent patients.