Color Vision Impairment in Schizophrenia May Be Due to Medication

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The Cambridge Colour Test was used to assess color vision by the utility of 2 subtests, the Trivector and Ellipse tests.
The Cambridge Colour Test was used to assess color vision by the utility of 2 subtests, the Trivector and Ellipse tests.

Patients with schizophrenia may experience impaired color vision due to the disorder and antipsychotic medications, according to a study published in Schizophrenia Research.

In this study, researchers culled patients with schizophrenia and individuals who did not have schizophrenia from the Psychosocial Care Center and the general population, respectively. Individuals in the schizophrenia group used the following typical and atypical antipsychotic medications: haloperidol (n=19), chlorpromazine (n=9), levomepromazine (n=1), quetiapine (n=11), olanzapine (n=8), risperidone (n=7), clozapine (n=2), and ziprasidone (n=1). Participants across both groups were between the ages of 25 and 45 years old.

Based on the Trivector test, patients in the schizophrenia group had higher thresholds along the Protan (U=6, P <.01, r=0.54), Deutan (U=36, P <.01, r=0.51), and Tritan (U=39, P <.01, r=0.62) vectors when compared with individuals in the control group. There were also substantial deviations in the areas of Ellipse 1, [U=8, P <.001, r=0.51], Ellipse 2, [U=15, P =.007, r=0.33] and Ellipse 3, [U=10, P <.001, r=0.45] among the groups.

When factoring in medications, comparisons between the schizophrenia typical and atypical medication groups revealed differences in chromatic discrimination thresholds for Protan axis (U=48, P =.007, r=0.41) and Tritan axis (U=31, P =.001, r=0.30), with no differences for Deutan axis (U=65, P =.089). There were disparities between the schizophrenia typical and schizophrenia atypical medication groups for Ellipse 2 (U=74, P =.011, r=0.36) and Ellipse 3 (U=86, P =.033, r=0.31). In ellipse angle, there were disparities between the schizophrenia typical and schizophrenia atypical medication groups: Ellipse 1 (P =.040, r=0.27), Ellipse 2 (P =.001, r=0.42), and Ellipse 3 (P =.031, r=0.28). Schizophrenia typical and atypical medication groups displayed differences in Ellipses areas also: Ellipse 1 (P <.001, r=0.58), Ellipse 2 (P =.040, r=0.25) and Ellipse 3 (P =.012, r=0.33).

Researchers conclude that "results suggest that [schizophrenia] may affect color vision, and/or that antipsychotic medication affects color vision in the disorder." They also stressed that results should be cautiously inferred based on limitations such as long-term medication use and the exclusion of nonmedicated patients with schizophrenia.

Reference

Fernandes TMP, Silverstein SM, Butler PD, et al. Color vision impairments in schizophrenia and the role of antipsychotic medication type [published online September 7, 2018]. Schizophr Res. doi: 10.1016/j.schres.2018.09.002

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