Background: Despite years of research on acquired deficits in color perception (cerebral achromatopsia/dyschromatopsia), there is still limited knowledge regarding the expression and prevalence of these deficits, although they are generally considered to be rare. Investigating patients with achromatopsia
can provide important insights into the cortical areas involved in color perception, including the respective roles of the two hemispheres. Objective: The aim of this study was to explore color perception deficits in a large group of patients with stroke in the back of the brain.
Method: The data presented are from the Back of the Brain project (BoB), a study assessing visual perception in a large group of stroke patients, recruited based
on lesion location in the areas supplied by the posterior cerebral artery. 63 stroke patients as well as 44 matched controls were tested with the Farnsworth D-15 Dichotomous Color Blindness Test to assess color perception. Abnormality of performance was determined using single case statistics. In patients with abnormal performance, the lateralization of the lesions was examined and a qualitative analysis of the patterns of the patients’ color difficulties was performed.
Results: 27% of the patients (17/63) showed significant problems with color discrimination. Of the total patient sample, 44% of patients with bilateral lesions, 34% with left hemisphere lesions and 10% with right hemisphere lesions had significant color discrimination impairments. There was a great diversity in both the patterns and severity of the impairments.
Conclusions: The results suggest that, rather than being a rare occurrence, color perception difficulties after a PCA stroke are actually rather common, and that difficulties with perceiving colors after stroke vary greatly in expression and severity. The findings also point towards a left hemispheric domination in color processing, contradicting previous reports suggesting a possible right hemispheric specialization.